Get ready for a sweet treat that will have everyone raving—Monster Cookie Fudgy Brownies are absolute magic in dessert form. Picture the fudgiest, richest brownies swirled with a thick, chewy monster cookie dough packed with chocolate chips, oats, peanut butter, and mini M&M’s. Each bite is the perfect balance of gooey chocolate, nutty goodness, and a festive crunch, making them an irresistible crowd-pleaser for parties, holidays, or just a Saturday night at home. These Monster Cookie Fudgy Brownies are truly the dessert mashup you didn’t know you needed.

Monster Cookie Fudgy Brownies Recipe - Recipe Image

Ingredients You’ll Need

These Monster Cookie Fudgy Brownies are built from two decadent layers, and each ingredient plays a starring role—creating that signature chocolaty depth, cookie chewiness, and pops of colorful crunch. Here’s what you’ll need and why every item matters!

White granulated sugar: Essential for sweetness and helping the brownies become deliciously glossy and fudgy.
Large eggs + Egg yolk: Bring richness, structure, and that perfectly chewy texture to both the brownies and cookies.
Unsalted butter: Adds creamy flavor; make sure some is at room temperature for the cookie dough and the rest is melted for the brownies.
Oil (canola or vegetable): Keeps the brownies extra moist and fudgy.
Pure vanilla extract: Deepens the flavor and brings warmth to both layers.
All-purpose flour: Provides the structure for both brownie and cookie layers.
Unsweetened cocoa powder (dutch process): The secret to ultra-rich, intense chocolatey brownie flavor.
Cornstarch: Makes the brownies softer and the cookie layer perfectly tender.
Salt: Balances out the sweetness and enhances all the chocolatey, nutty notes.
Semi-sweet chocolate chips: Melt into fudgy puddles for deeply satisfying chocolate bursts.
Milk chocolate chips: Add sweet, creamy pockets for extra indulgence.
Baking soda + Baking powder: Help the cookie layer rise and get perfectly chewy without being cakey.
Brown sugar (packed light or dark): Lends moisture, a subtle molasses flavor, and irresistible chewiness to the cookie dough.
Peanut butter (creamy): Makes the monster cookie layer rich, nutty, and classic.
Quick oats: Bring that signature monster-cookie chew and slightly hearty texture.
Mini chocolate chips: Ensure every bite of cookie dough is studded with melty chocolate.
Mini M&M’s: Add bits of color and extra crunch, making these brownies so much fun!

How to Make Monster Cookie Fudgy Brownies

Step 1: Make the Monster Cookie Dough

Start by mixing up your monster cookie dough, which will later become the star-studded crown of your Monster Cookie Fudgy Brownies. In a medium bowl, whisk together 1/2 cup all-purpose flour, 1 tsp cornstarch, 1/2 tsp baking soda, 1/8 tsp baking powder, and 1/4 tsp salt. In a separate larger bowl, beat 1/4 cup room temperature unsalted butter, 1/3 cup brown sugar, and 1/8 cup granulated sugar for a minute until light and creamy. Mix in 1/4 cup creamy peanut butter until smooth, then add 1 tsp vanilla and 1 large egg, beating just until combined. Slowly add your dry mixture to the wet, then fold in 1/2 cup quick oats, 1/2 cup mini chocolate chips, and 1/2 cup mini M&M’s. Cover the bowl and chill for about 40 minutes, letting the flavors mingle and the dough firm up for easy shaping.

Step 2: Prepare and Preheat

While your cookie dough chills, get your brownie setup ready! Preheat your oven to 325°F. Grease a 9×9-inch baking pan with nonstick spray and line it with parchment paper along the bottom and two sides. This makes lifting the brownies out for slicing a total breeze later, and ensures perfect brownie squares every time.

Step 3: Mix the Brownie Dry Ingredients

In a medium bowl, whisk together 1/2 cup all-purpose flour, 3/4 cup Dutch-process cocoa powder, 1 tbsp cornstarch, and 1/4 tsp salt. This simple step guarantees the cocoa blends evenly throughout and helps create the ultimate fudgy, never-cakey brownie texture.

Step 4: Beat the Wet Ingredients for Brownies

Using a stand mixer with the whisk attachment, beat together 1 1/3 cups white sugar, 2 large eggs, and 1 egg yolk for a full 5 minutes. This may seem like a long time, but it’s the secret to getting a shiny, crinkly top and a dense, brownie-fudge interior. While those are mixing, melt 5 tbsp unsalted butter and let it cool just a bit. You want the egg mixture to become pale and tripled in volume.

Step 5: Finish the Brownie Batter

Pour the cooled melted butter, 1/3 cup oil, and 1 tsp pure vanilla extract into the whipped eggs and sugar, mixing on low just until blended. Remove from the mixer and gently fold in your flour-cocoa mixture using a spatula, being careful not to knock the air out. Finally, stir in 1/2 cup each of semi-sweet chocolate chips and milk chocolate chips for that double-chocolate punch. Spread the batter evenly in your prepared pan.

Step 6: Layer and Bake

Bake the brownie base by itself for 15 minutes first—this gives it a head start and protects that fudgy finish. Meanwhile, pull your monster cookie dough from the fridge and flatten small handfuls into discs. After the first 15 minutes, carefully place the cookie dough discs over the partially-baked brownies, covering the top. Pop the whole pan back in the oven for another 20 minutes, then loosely cover it with foil to prevent over-browning and bake an additional 5 to 10 minutes. At this point, both the cookie layer and brownie should be set. Let your Monster Cookie Fudgy Brownies cool completely on a rack before slicing—a tough wait, but so worth it for that perfect fudgy bite!

How to Serve Monster Cookie Fudgy Brownies

Garnishes

Bring out the wow factor by scattering extra mini M&M’s and mini chocolate chips over the brownies while they’re still a tad warm. A sprinkle of flaky sea salt elevates the chocolate and peanut butter flavors, while a light dusting of powdered sugar adds a bakery-style finish. For a really decadent bite, try a drizzle of warm peanut butter or melted chocolate over each piece before serving.

Side Dishes

Monster Cookie Fudgy Brownies stand tall on their own, but for an extra-special treat, serve them with a scoop of vanilla bean ice cream or a dollop of whipped cream. A fresh fruit salad or a cold glass of milk pairs beautifully to cut through the richness. For party platters, brownies go great next to classics like chocolate chip cookies or butterscotch blondies.

Creative Ways to Present

Slice the brownies into bite-sized squares for a cookie bar platter, or cut them into wedges and serve in parchment-lined cones for a mess-free grab-and-go dessert. For celebrations, pack individual squares in decorative boxes for the cutest edible gifts. You can even bake the Monster Cookie Fudgy Brownies in muffin tins for adorable brownie-cookie cups—perfect for bake sales or birthday treats!

Make Ahead and Storage

Storing Leftovers

Store any leftover Monster Cookie Fudgy Brownies in an airtight container at room temperature for up to 3 days. They’ll stay soft and flavorful thanks to the peanut butter and brown sugar in the cookie layer. Just be sure they’re completely cooled before storing to prevent condensation and soggy edges.

Freezing

To freeze, wrap individual brownie squares in plastic wrap, then tuck them in a freezer-safe bag or airtight container. They’ll hold up beautifully for up to 2 months. Thaw them at room temperature or gently reheat for that fresh-out-of-the-oven taste.

Reheating

To reclaim that just-baked gooeyness, microwave a chilled or frozen brownie for 10-15 seconds—just enough to warm the chocolate chips and soften each bite. You can also pop them in a 300°F oven for 5 minutes if you’re reheating a whole pan or several squares at once.

FAQs

Can I make Monster Cookie Fudgy Brownies without peanut butter?

Absolutely! If you or your guests have allergies, simply swap the peanut butter for sunflower seed butter, almond butter, or even cookie butter. The texture and flavor will be a bit different, but still delicious and safe for everyone.

What type of oats should I use?

Quick oats work best in monster cookies, lending that signature chewy texture without being too coarse. Avoid steel-cut oats, but you can substitute regular old-fashioned oats if that’s what you have on hand—just pulse them a few times in a food processor first.

Can I double the recipe for a bigger crowd?

Definitely! Just double all ingredients and bake in a 9×13-inch pan. Increase the first bake to about 20 minutes before adding the cookie layer, then keep a close eye for doneness in the final bake. Enjoy even more Monster Cookie Fudgy Brownies to share!

Why do I need to chill the cookie dough?

Chilling the dough allows the moisture to distribute evenly and firms up the fat, which helps the cookies keep their shape and creates that perfectly thick, chewy cookie layer atop your brownies. Don’t skip it—the texture payoff is huge!

How do I know when the brownies are done baking?

When the timer goes off, gently shake the pan: there should be no jiggle in the center and the cookie dough should look set and lightly golden. Brownies continue to firm up as they cool, so a toothpick may come out a little fudgy—that’s perfect for this recipe!

Final Thoughts

If you’ve been searching for a dessert that’s as fun to make as it is to eat, let Monster Cookie Fudgy Brownies be your next baking adventure! They combine everything we love about both classic brownies and playful monster cookies into one over-the-top treat. Give them a try—you’ll be hooked from the very first bite!

Monster Cookie Fudgy Brownies Recipe

★★★★★

5.2 from 5 reviews

Author: Zoe
Total Time: 1 hour 5 minutes
Yield: 16 brownies 1x
Diet: Vegetarian

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Description

Indulge in the ultimate dessert mashup with these Monster Cookie Fudgy Brownies! A layer of rich, fudgy brownie topped with a chewy monster cookie layer loaded with oats, chocolate chips, and colorful M&M’s. These decadent brownies are a perfect treat for any occasion.

Instructions

Monster Cookies
Mix together dry ingredients in a bowl. Beat butter and sugars until light and fluffy. Add peanut butter, vanilla, and egg. Mix in dry ingredients, oats, chocolate chips, and M&M’s. Chill dough.
Brownies
Preheat oven. Whisk dry ingredients in a bowl. Beat sugar and eggs until fluffy. Mix in melted butter, oil, and vanilla. Fold in dry ingredients and chocolate chips. Spread batter in pan. Top with chilled cookie dough discs. Bake until set. Cool completely before cutting.