Monster Cookie Fudgy Brownies Recipe

If you’ve ever dreamed of the ultimate mashup between two classic treats, Monster Cookie Fudgy Brownies is about to be your dessert obsession. Imagine a thick, fudgy brownie base layered with buttery, peanut-studded monster cookie dough—each bite bringing you a burst of chocolate, oats, and colorful mini M&Ms. This recipe is a joyful blend of soft, chewy, and gooey textures that’s perfect for celebrations, bake sales, or satisfying those “just one more bite” cravings. Making these at home is much simpler than you’d think, and the results are spectacular every single time.

Ingredients You’ll Need

Don’t let the slightly longer ingredient list fool you—every item is easy to find and has a special role to play in creating the perfect Monster Cookie Fudgy Brownies. Together, they deliver layers of flavor, a melt-in-your-mouth fudgy texture, and a gorgeous pop of color that’s seriously irresistible.

• White granulated sugar: Essential for sweetness and helps create that shiny, crackly brownie top.
• Large eggs + egg yolk: Provide structure and extra richness for the brownies’ signature fudgy bite.
• Unsalted butter: Brings buttery richness to both brownie and cookie layers—make sure some is room temperature for the cookies.
• Oil (canola or vegetable): Keeps the brownie crumb super moist and tender.
• Pure vanilla extract: Deepens flavor and adds warmth to both elements.
• All-purpose flour: The backbone that gives brownies and cookies their structure.
• Unsweetened cocoa powder (dutch process): Lends a bold, chocolatey bitterness for authentic brownie depth.
• Cornstarch: Keeps both brownie and cookie dough extra soft and chewy.
• Salt: Brightens and balances all the sweet notes—never skip it!
• Semi-sweet chocolate chips: Add melted chocolate pockets to the brownies.
• Milk chocolate chips: For extra richness and a mellow chocolate contrast.
• Baking soda & Baking powder: Offer lift and tenderness to the cookie dough.
• Brown sugar (light or dark): Adds moisture and a hint of caramel flavor to the cookies.
• Peanut butter (creamy): The signature monster cookie twist—nutty, creamy, and rich.
• Quick oats: Add hearty, chewy texture, making the cookie topping truly monster-worthy.
• Mini chocolate chips & mini M&Ms: A colorful, fun finish and plenty of gooey, chocolatey bursts.

How to Make Monster Cookie Fudgy Brownies

Step 1: Make the Monster Cookie Dough

Begin by mixing together the flour, cornstarch, baking soda, baking powder, and salt in a medium bowl. In a separate large bowl, beat the butter, brown sugar, and white sugar for a full minute. This creates a light and creamy base—don’t rush it! Next, mix in the creamy peanut butter until everything looks fluffy and well incorporated. Add the vanilla and egg, then mix just until combined, scraping down the bowl as needed to get every bit in. Slowly fold in the dry ingredients, then stir in oats, mini M&Ms, and chocolate chips. Cover the dough and let it chill in the fridge for 40 minutes so it firms up and becomes easy to handle later.

Step 2: Prepare the Brownie Batter

When your cookie dough is nearly done chilling, start working on the fudgy brownie layer—the heart of every Monster Cookie Fudgy Brownies batch! Preheat your oven to 325F and prep a 9X9 pan with non-stick spray and parchment paper for easy removal after baking. In one bowl, whisk together flour, cocoa powder, cornstarch, and salt. In a stand mixer, combine the sugar, eggs, and additional egg yolk. Beat this mixture with a whisk attachment for a full 5 minutes to get it light and fluffy. Melt your butter so it has time to cool slightly, then gently mix it in with oil and vanilla. Take the bowl off the mixer, and with a rubber spatula, fold in the dry mix. Add the chocolate chips last, being careful not to overmix.

Step 3: Assemble and Layer

Pour your brownie batter into the prepared pan, spreading it right up to the corners with a spatula. Bake for 15 minutes—just enough time for the top to set, but the center should still be soft and gooey. Now, pull your chilled monster cookie dough from the fridge. Take small handfuls, flatten them into discs, and gently press them on top of the par-baked brownies, covering as much of the surface as possible with slightly overlapping bits for that signature marbled, chunky look.

Step 4: Bake to Perfection

Return the pan to the oven and bake for another 20 minutes. Then, loosely cover with foil to prevent over-browning, and bake an additional 5–10 minutes. You’ll know your Monster Cookie Fudgy Brownies are done when the top is golden, the brownie doesn’t jiggle, and the cookie layer is perfectly set. Place the pan on a wire rack and let them cool completely—resist cutting until they’re room temperature for perfectly defined squares.

How to Serve Monster Cookie Fudgy Brownies

Garnishes

Add a finishing touch by sprinkling a few extra mini M&Ms or chocolate chips right after baking. For a decadent flourish, drizzle with melted chocolate or a dusting of powdered sugar once cool—each bite becomes even more tempting!

Side Dishes

These brownies are absolute showstoppers with a scoop of vanilla bean ice cream, or alongside a tall glass of chilled milk. For grown-up pairings, consider serving with coffee or espresso for the ultimate afternoon treat.

Creative Ways to Present

Cut Monster Cookie Fudgy Brownies into bite-sized squares for party platters, layer them in jars with ice cream for a brownies-and-cookie parfait, or stack them high with a candle for a birthday dessert that’s pure joy.

Make Ahead and Storage

Storing Leftovers

If you have any leftovers—though they tend to vanish!—simply place your Monster Cookie Fudgy Brownies in an airtight container at room temperature. They’ll stay soft, chewy, and delicious for up to four days, making them perfect for packed lunches or snacking on the go.

Freezing

For longer storage, these brownies freeze like a dream. Let them cool completely, then wrap each square individually in plastic wrap before placing them in a freezer-safe bag. They’ll keep for up to three months, ready whenever your sweet tooth strikes.

Reheating

To bring out that just-baked gooeyness, pop a brownie square in the microwave for about 10–15 seconds. The chocolate chips will melt slightly, and the cookie layer will become extra soft, as if fresh from the oven.

FAQs

Can I use crunchy peanut butter instead of creamy?

Absolutely! Using crunchy peanut butter will add extra texture and tiny peanut pieces to the cookie layer, making the Monster Cookie Fudgy Brownies even more satisfying.

Why is chilling the cookie dough important?

Chilling helps the cookie dough firm up, making it easier to handle and shape into discs that sit on top of the brownies without spreading too quickly while baking.

Can I make this recipe gluten free?

You sure can! Swap the all-purpose flour for a measure-for-measure gluten free blend and ensure your oats are certified gluten free. The results are just as delightful and fudgy.

Do I have to use both semi-sweet and milk chocolate chips?

Mixing both types gives layers of chocolatey complexity, but you can absolutely use only one kind if you prefer or adjust based on what’s in your pantry.

How do I cut clean brownie squares?

For picture-perfect slices, let your Monster Cookie Fudgy Brownies cool completely, then use a sharp, warm knife and wipe clean after each cut. This helps guarantee neat edges every time.

Final Thoughts

Trust me—the hardest part of making Monster Cookie Fudgy Brownies is waiting for them to cool before sneaking a bite. They’re truly the ultimate treat for anyone who loves the best of both decadent brownies and colorful, peanut butter-loaded cookies. If you’re ready for a jaw-dropping dessert, bake a batch and see just how quickly they become a family favorite!

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