Name: Chewy Monster Cookie Fudgy Brownies
Prep time: 40 min
Cook time: 40 min
Total time: 4 h 20 min
Yield: 12 servings
Ingredients: 1 1/3 cup White granulated sugar; 2 Large eggs; 1 Egg yolk; 5 tbsp Unsalted butter; 1/3 cup Canola or vegetable oil; 1 tsp Pure vanilla extract; 1/2 cup All-purpose flour (for brownie); 3/4 cup Unsweetened cocoa powder, Dutch process; 1 tbsp Cornstarch (for brownie); 1/4 tsp Salt; 1/2 cup Semi-sweet chocolate chips; 1/2 cup Milk chocolate chips; 1/2 cup All-purpose flour (for cookie layer); 1 tsp Cornstarch (for cookie layer); 1/2 tsp Baking soda

Monster Cookie Fudgy Brownies – prepare to embark on a truly extraordinary culinary adventure that flawlessly marries two of the most adored dessert titans! Imagine sinking your teeth into a treat where the irresistible chewiness of a classic monster cookie, brimming with peanut butter, oats, and vibrant M&M’s, flawlessly blends with the deep, dense, and utterly decadent richness of a fudgy brownie. This isn’t just a dessert; it’s a masterful creation designed to satisfy every sweet craving in one gloriously cohesive bite, promising an explosion of flavor and texture that will leave you utterly spellbound.

While both brownies and monster cookies hold esteemed places in the pantheon of American comfort desserts, their fusion into these incredible Monster Cookie Fudgy Brownies represents a modern marvel of ingenuity. People adore this dish not just for its delightful novelty, but for the perfect harmony of textures and flavors it consistently delivers. The crispy, slightly chewy edges, the unbelievably gooey center, the delightful crunch of candy-coated chocolates, and the unmistakable nutty undertones from the peanut butter create a symphony for the palate. It’s the ultimate crowd-pleaser, a guaranteed showstopper at any gathering, and quite possibly, the most satisfying dessert you will ever bake and enjoy. I am absolutely thrilled for you to experience this magnificent creation!

Ingredients:

Unsalted Butter: 1 cup (226g) total. You’ll need some softened for the cookie dough and some melted for the brownie base. Using unsalted butter allows us to perfectly control the salt balance in our Monster Cookie Fudgy Brownies. I always opt for it!
Granulated Sugar: 1 ¾ cups (350g) total. This sweet foundation will be carefully divided between our two sensational layers.
Light Brown Sugar: 1 ½ cups (300g) packed. This is truly the secret to achieving that irresistible chewiness and depth of flavor in both the brownie and the cookie dough. Make sure it’s firmly packed into your measuring cup!
Large Eggs: 4 total, ideally at room temperature. Room temperature eggs emulsify better with other ingredients, creating a smoother, more uniform batter for both layers.
Pure Vanilla Extract: 3 teaspoons total. Please, do not skimp on good quality vanilla! It’s an unsung hero, enhancing all the other wonderful flavors.
All-Purpose Flour: 2 cups (240g) total, spooned and leveled. I always recommend spooning your flour into the measuring cup and then leveling it off with a straight edge to avoid over-measuring, which can lead to dry baked goods.
Unsweetened Cocoa Powder: ¾ cup (65g). For these fudgy brownies, I absolutely adore using Dutch-processed cocoa powder. It gives a beautifully deep, dark color and a wonderfully mellow, rich chocolate flavor that’s just divine.
Baking Powder: ½ teaspoon. This is our leavening agent for the brownie layer, helping it achieve that perfect rise without becoming cakey.
Baking Soda: 1 teaspoon. Specifically designated for our monster cookie dough layer, baking soda reacts with the brown sugar and peanut butter to give those cookies their signature soft, chewy texture and slight lift.
Salt: 1 teaspoon total. A crucial ingredient! Salt is vital for balancing the sweetness and enhancing all the delicious flavors in both layers.
Semi-Sweet Chocolate Chips: 1 cup (170g) for incorporating into the brownie batter, ½ cup (85g) mini chocolate chips specifically for the cookie dough, and then an additional ½ cup (85g) for our optional, but highly recommended, fudge drizzle.
Creamy Peanut Butter: 1 cup (250g). For the best results in your monster cookie layer, I strongly recommend using a classic, creamy peanut butter, like Jif or Skippy. Natural peanut butters tend to separate and can alter the texture of the cookie dough too much.
Old-Fashioned Rolled Oats: 1 cup (90g). These are absolutely essential for that authentic, wonderfully chewy texture that defines a true monster cookie. Quick oats can be used in a pinch, but the texture won’t be quite the same.
M&M’s Candies: 1 cup (170g) for mixing into the cookie dough, plus a generous handful extra for sprinkling on top before baking. These colorful little gems provide a delightful crunch and a pop of visual fun that is simply non-negotiable for “Monster” brownies!
Heavy Cream: 2 tablespoons (30ml) for the optional, decadent fudge drizzle. Alternatively, you can use 1 tablespoon of unsalted butter if you don’t have heavy cream on hand.

Prepping Your Workspace and Oven:

Before we dive into the deliciousness, let’s get our kitchen ready! This crucial first step ensures a smooth baking process and perfectly baked Monster Cookie Fudgy Brownies.

Preheat Your Oven: My first order of business is always to get the oven preheating. Turn your oven to 350°F (175°C). This allows the oven to reach and maintain a consistent temperature, which is so important for even baking.
Prepare Your Baking Pan: Grab a 9×13-inch baking pan. I like to line mine with parchment paper, leaving an overhang on the longer sides. This acts like a sling, making it incredibly easy to lift the entire batch of brownies out of the pan once they’re cooled. Trust me, this trick saves so much hassle! If you don’t have parchment, you can thoroughly grease and flour the pan, or use a non-stick spray, but the parchment really is a game-changer for clean removal and easy slicing.

Why proper pan preparation matters:

Lining the pan not only makes removal effortless but also ensures a cleaner cut, especially with a layered treat like our Monster Cookie Fudgy Brownies. You don’t want any sticky situations trying to pry these beauties out!

Crafting the Rich Fudgy Brownie Base:

This is where the magic begins – creating an incredibly rich, dense, and super fudgy brownie layer that will be the foundation of our masterpiece. We’re aiming for a crackly top and a gooey center.

Melt the Butter: In a medium microwave-safe bowl or a small saucepan over low heat, melt ½ cup (113g) of the unsalted butter. Once melted, set it aside to cool slightly. We don’t want it scorching hot when we add it to our sugar and eggs.
Combine Sugars and Eggs: In a large mixing bowl, whisk together 1 cup (200g) of granulated sugar and 1 cup (200g) of light brown sugar (packed). Crack in 2 large eggs and add 1 teaspoon of vanilla extract. Whisk vigorously for about 2-3 minutes until the mixture is light in color, thick, and very well combined. This process incorporates air and creates that beautiful, shiny, crackly top that everyone loves on a good brownie.
Incorporate Melted Butter: Gradually pour the slightly cooled melted butter into the egg and sugar mixture while continuously whisking. Continue to whisk until everything is thoroughly incorporated and smooth. This creates a luxurious, glossy base.
Sift in Dry Ingredients: In a separate bowl, whisk together the ¾ cup (65g) unsweetened cocoa powder, ½ teaspoon baking powder, ½ teaspoon salt, and 1 cup (120g) of all-purpose flour. I like to sift my dry ingredients, especially cocoa powder, to ensure there are no lumps and everything is evenly distributed.
Gently Fold Dry into Wet: Add the dry ingredient mixture to the wet mixture. Using a spatula, gently fold until just combined. Be careful not to overmix! Overmixing develops the gluten in the flour, which can lead to tough, cakey brownies rather than the dense, fudgy texture we’re after. A few streaks of flour are perfectly fine; they’ll disappear during baking.
Add Chocolate Chips: Fold in 1 cup (170g) of the semi-sweet chocolate chips. These little pockets of melted chocolate will elevate the fudginess to another level.
Spread the Brownie Batter: Pour the brownie batter into your prepared 9×13-inch pan. Use your spatula to spread it evenly into a single layer. Don’t worry if it seems a little thick; that’s exactly what we want for a truly fudgy brownie base. Set this aside while we prepare our monster cookie dough.

Achieving that perfect brownie texture:

The key to these Monster Cookie Fudgy Brownies is that rich brownie bottom. The combination of brown and granulated sugars, combined with precise mixing techniques, ensures a dense, chewy, and gloriously fudgy texture. Resisting the urge to overmix is paramount here!

Whipping Up the Delightful Monster Cookie Dough Layer:

Now for the “monster” part! This cookie dough is packed with flavor and texture, perfectly complementing our rich brownie base.

Cream Butter and Sugars: In another large mixing bowl, or the bowl of a stand mixer fitted with the paddle attachment, cream together the remaining ½ cup (113g) softened unsalted butter, ½ cup (100g) granulated sugar, and ½ cup (100g) packed light brown sugar. Beat on medium speed until the mixture is light, fluffy, and pale in color, usually about 3-4 minutes. This creaming process aerates the butter and sugar, contributing to a softer cookie.
Add Peanut Butter, Egg, and Vanilla: Scrape down the sides of the bowl. Add the 1 cup (250g) of creamy peanut butter, the remaining 2 large eggs, and the remaining 2 teaspoons of vanilla extract. Beat on medium speed until well combined, scraping the bowl once or twice to ensure everything is incorporated. The mixture will look rich and invitingly smooth.
Combine Dry Ingredients: In a separate medium bowl, whisk together the remaining 1 cup (120g) of all-purpose flour, 1 teaspoon baking soda, and the remaining ½ teaspoon salt.
Gradually Add Dry to Wet: With the mixer on low speed, gradually add the dry ingredients to the wet ingredients. Mix just until combined, being careful not to overmix. Just like with the brownies, overmixing can lead to tough cookies, and we want these to be perfectly tender and chewy.
Fold in Monster Mix-ins: Remove the bowl from the mixer (if using) or grab your trusty spatula. Gently fold in the ½ cup (85g) mini chocolate chips, the 1 cup (90g) old-fashioned rolled oats, and 1 cup (170g) of M&M’s candies. Make sure these delicious additions are evenly distributed throughout the dough. The oats will absorb some moisture and provide that characteristic chew.

The essence of a monster cookie:

The beauty of this monster cookie dough layer lies in its incredible mix of textures and flavors. From the creamy peanut butter to the chewy oats and the colorful crunch of M&M’s, every bite will be an adventure!

Assembling and Baking Your Monster Cookie Fudgy Brownies:

We’re almost there! Now it’s time to bring these two amazing layers together and bake them to perfection.

Layer the Cookie Dough: Carefully dollop spoonfuls of the monster cookie dough over the brownie batter in the prepared pan. The cookie dough will be quite thick, so it’s easiest to drop small mounds and then gently spread them out with the back of a spoon or a small offset spatula. Try to cover the entire brownie layer as evenly as possible without pressing down too hard, which could mix the layers.
Top with More M&M’s: This is a fun optional step, but one I always do! Sprinkle an additional generous handful of M&M’s candies over the top of the cookie dough layer. Not only does this add more crunch and chocolatey goodness, but it also makes the Monster Cookie Fudgy Brownies look absolutely stunning and clearly announces what deliciousness lies within!
Bake to Perfection: Place the pan in your preheated 350°F (175°C) oven. Bake for approximately 35-45 minutes. Baking times can vary depending on your oven, so keep an eye on them.
Check for Doneness: The brownies are done when the edges are set, and a wooden skewer or toothpick inserted into the center of the brownie layer (not just the cookie dough) comes out with moist crumbs, but no wet batter. The cookie dough layer will look golden brown and slightly firm to the touch. It’s better to under-bake slightly for maximum fudginess than to over-bake and end up with dry brownies.
Cool Completely: This is arguably the hardest step: patience! Remove the pan from the oven and place it on a wire rack to cool completely. This means at least 2-3 hours, or even longer. For the cleanest cuts and best texture, I often let them cool at room temperature and then pop them in the refrigerator for an hour or two. Do not try to cut them warm! They will be a gooey, delicious mess, but not in a neatly sliceable way.

The golden rule of cooling:

Cooling is critical for the structure and texture of these layered bars. It allows the brownie layer to set into its fudgy glory and the cookie layer to firm up, making for perfect, clean slices. Embrace the wait; it’s worth it!

Creating the Decadent Fudge Drizzle (Optional but Highly Recommended):

Adding a simple fudge drizzle on top takes these Monster Cookie Fudgy Brownies from amazing to absolutely unforgettable. It’s an extra touch of richness that is so easy to do.

Melt Chocolate for Drizzle: Once your Monster Cookie Fudgy Brownies are completely cooled (this is important, as you don’t want the drizzle to just melt into the bars), place the remaining ½ cup (85g) semi-sweet chocolate chips into a small microwave-safe bowl.
Heat Cream: In a separate small microwave-safe bowl, or a very small saucepan, gently heat the 2 tablespoons (30ml) of heavy cream (or 1 tablespoon of butter) until it’s just simmering or very hot, but not boiling.
Combine for Ganache: Pour the hot cream over the chocolate chips. Let it sit for about 1-2 minutes to allow the chocolate to melt. Then, whisk gently until the mixture is completely smooth and glossy. You’ll have a beautiful, rich ganache. If there are still a few unmelted chips, you can microwave it for another 10-15 seconds, then whisk again.
Drizzle and Set: Using a spoon, drizzle the warm fudge ganache artfully over the cooled brownies. You can make zigzags, swirls, or just random lines – whatever makes you happy! Let the drizzle set for at least 15-30 minutes at room temperature, or pop the pan back into the fridge for 10 minutes to speed up the setting process.

The beauty of a simple ganache:

This quick fudge drizzle isn’t just for looks; it adds another layer of deep chocolate flavor and a luxurious texture that truly elevates the entire Monster Cookie Fudgy Brownie experience. It’s a small effort for a big reward!

Cooling, Slicing, and Enjoying Your Monster Cookie Fudgy Brownies:

The final, glorious steps before you get to indulge in your incredible creation.

Lift and Prepare for Slicing: Once the brownies are completely cooled and the fudge drizzle (if used) has set, carefully use the parchment paper overhang to lift the entire slab of Monster Cookie Fudgy Brownies out of the pan and onto a cutting board. This makes slicing so much easier and cleaner.
Slice with Precision: Using a large, sharp knife, slice the brownies into your desired size squares or rectangles. For clean cuts, I like to wipe my knife clean with a damp paper towel after every few cuts. This prevents the layers from sticking and smearing. You can make them into generous squares for a hearty treat or smaller bites if you’re serving a crowd. I usually go for 12 or 16 squares, but sometimes, a truly monstrous brownie calls for just 9 larger pieces!
Serve and Enjoy: Arrange your magnificent Monster Cookie Fudgy Brownies on a serving platter. They are fantastic at room temperature, but if you prefer them a little firmer, they can be stored in the refrigerator. Each bite is a symphony of fudgy brownie, chewy peanut butter cookie, chocolate chips, and delightful M&M’s. These are truly an experience!
Storage: Store any leftover brownies in an airtight container at room temperature for up to 3-4 days, or in the refrigerator for up to a week. If you’ve made a large batch, these also freeze beautifully for up to 2-3 months. Just wrap individual pieces tightly in plastic wrap and then place them in a freezer-safe bag or container. Thaw at room temperature when ready to enjoy.

The ultimate indulgence:

These Monster Cookie Fudgy Brownies are more than just a dessert; they’re a celebration in every square. Perfect for parties, potlucks, or simply as a special treat for yourself and your loved ones. Get ready for rave reviews!

Conclusion:

And there you have it, my friends! We’ve journeyed through the creation of what I truly believe is one of the most exciting and indulgent treats you’ll ever pull from your oven. If you’ve been searching for that perfect dessert that absolutely wows everyone, look no further. This recipe isn’t just about baking; it’s about crafting an experience, a moment of pure, unadulterated joy that lingers long after the last crumb has vanished. I cannot stress enough why these are a must-try. Imagine the best of both worlds colliding in a symphony of texture and taste: the chewy, peanut butter, oat-filled delight of a monster cookie, perfectly swirled into the rich, dense, and utterly irresistible foundation of a truly fudgy brownie. It’s a culinary masterpiece that perfectly balances the nostalgic charm of classic cookies with the sophisticated depth of a gourmet brownie.

What makes them truly stand out is that unparalleled texture – a slight crisp on the edges, a gooey, almost molten center, packed with vibrant colors and diverse flavors from the M&M’s and chocolate chips. Every single bite is an adventure, a delightful surprise that keeps you coming back for more. This isn’t just another brownie recipe; it’s an elevated dessert experience that promises to become a staple in your baking repertoire. I can confidently say that once you taste the glorious combination of our Monster Cookie Fudgy Brownies, you’ll understand why I’m so incredibly enthusiastic about them. They’re a celebration in every square, perfect for any occasion, or simply for brightening up a regular Tuesday evening.

Serving Up Sweet Perfection: My Favorite Ways to Enjoy

Now, while these brownies are undeniably spectacular on their own – truly a standalone dessert capable of stealing the show – I always love to offer a few suggestions for how to elevate the experience even further. For a truly decadent treat, try serving a warm square of these brownies with a scoop of vanilla bean ice cream. The cold, creamy ice cream melting into the warm, fudgy brownie is a sensory delight that is simply unparalleled. A dollop of freshly whipped cream, perhaps lightly sweetened with a touch of vanilla or even a hint of espresso, also makes for an exquisite accompaniment, adding a lightness that beautifully contrasts the brownie’s richness. Don’t forget the classic pairing of a tall glass of cold milk, which is always a winner, especially for the younger crowd. For an adult twist, consider serving them alongside a steaming mug of strong coffee or a shot of espresso – the bitterness of the coffee perfectly cuts through the sweetness, creating a harmonious balance that is utterly divine. They also make fantastic additions to a dessert platter, cut into smaller, bite-sized pieces, inviting guests to sample a little bit of everything.

Endless Possibilities: Fun Variations to Try

But the fun doesn’t stop there! While the base recipe for these Monster Cookie Fudgy Brownies is perfect as is, I always encourage experimentation. Baking is an art, and your kitchen is your canvas! Feel free to play around with the ‘monster cookie’ elements. Instead of just M&M’s, try adding Reese’s Pieces for an extra peanut butter punch, or perhaps some chopped Snickers or Butterfinger bars for a different candy experience. You could swap out the chocolate chips for white chocolate chips, dark chocolate chunks, or even a mix of milk and white. For those who love nuts, a handful of chopped walnuts or pecans folded into the brownie batter would add an extra layer of crunch and flavor. You could also try adding a sprinkle of sea salt on top before baking to enhance all those sweet and savory notes. For a truly over-the-top creation, consider drizzling a simple caramel sauce or a ganache over the cooled brownies. The possibilities are truly endless, allowing you to tailor this recipe to your own specific cravings and preferences.

Your Turn: Bake, Share, and Inspire!

So, what are you waiting for? This is your invitation to step into the kitchen and create something truly special. I promise you, the aroma alone as these bake will be enough to get everyone excited. There’s something so incredibly satisfying about pulling a tray of these magnificent brownies from the oven, knowing you’ve created such a delicious masterpiece with your own hands. Don’t just read about them; go ahead and bake them! I am so excited for you to experience the sheer delight of these Monster Cookie Fudgy Brownies. Once you’ve had a chance to whip up a batch, I would absolutely love to hear about your experience. Did you stick to the recipe, or did you venture into some exciting variations? What was your favorite part? Did they disappear as quickly as they did in my house? Please, share your baking adventures and your delicious results! Your feedback and photos not only make my day but also inspire countless other home bakers in our community. Happy baking, everyone!