Name: Monster Cookie Fudgy Brownies Recipe
Prep time: 30 min
Cook time: 45 min
Total time: 1 h 15 min
Cuisine: American
Ingredients: 1 1/3 cup White granulated sugar; 2 Large eggs; 1 Egg yolk; 5 TBSP Unsalted butter; 1/3 cup Oil (canola or vegetable); 1 tsp Pure vanilla extract; 1/2 cup All-purpose flour; 3/4 cup Unsweetened cocoa powder (dutch process); 1 TBSP Cornstarch; 1/4 tsp Salt; 1/2 cup Semi-sweet chocolate chips; 1/2 cup Milk chocolate chips; 1/2 cup All-purpose flour; 1 tsp Cornstarch; 1/2 tsp Baking soda; 1/8 tsp Baking powder; 1/4 tsp Salt; 1/4 cup Unsalted butter (room temperature); 1/3 cup Brown sugar (packed light or dark); 1/8 cup White granulated sugar; 1/4 cup Peanut butter (creamy); 1 tsp Pure vanilla extract; 1 Large egg (room temperature); 1/2 cup Quick oats; 1/2 cup Mini chocolate chips; 1/2 cup Mini M&M’s

Jump to Recipe

If you’re searching for the ultimate mash-up of two iconic desserts, look no further than these Monster Cookie Fudgy Brownies. This irresistible treat brings together everything you love about classic monster cookies—peanut butter, oats, rainbow candies—and fuses them with incredibly rich, fudgy brownies. Every bite is a flavor-packed adventure, combining gooey chocolate decadence with bursts of texture and color. If you’ve ever craved the chewy satisfaction of a cookie and the melt-in-your-mouth bliss of a brownie all at once, you’re about to fall head over heels for this over-the-top dessert.

Monster Cookie Fudgy Brownies Recipe - Recipe Image

Ingredients You’ll Need

The ingredients list is refreshingly straightforward, but each component really earns its place here. From the unsweetened cocoa that makes the brownies deeply chocolatey, to the oats and mini M&M’s that give the cookie layer personality, you’ll see how every item stacks up for maximum flavor and texture.

White granulated sugar: Brings sweetness and helps achieve that glossy, cracking top on the brownies.
Large eggs & extra yolk: These deliver essential structure and mega fudginess to the brownie base.
Unsalted butter: A flavor and richness booster for both layers; use unsalted for best control.
Oil (canola or vegetable): Keeps your brownies extra moist and chewy.
Pure vanilla extract: Deepens all the flavors—don’t skip it!
All-purpose flour (2 uses): Provides the backbone for both brownie and cookie layers; measure carefully for best texture.
Unsweetened cocoa powder (Dutch process): Delivers that deep, luscious chocolate flavor in the brownies.
Cornstarch (2 uses): Adds tenderness to both batters, giving cookies a soft crumb and brownies extra richness.
Salt (2 uses): Balances out the sweetness and heightens all the flavors.
Semi-sweet chocolate chips: Melts into pools of gooey chocolate right inside the brownie layer.
Milk chocolate chips: Adds a sweet, creamy twist to the brownies—so good in every bite.
Baking soda & baking powder: Helps your cookie layer rise just the right amount, so it’s soft and chewy but never cakey.
Brown sugar (packed light or dark): Adds a lovely caramel depth to the monster cookie top.
Peanut butter (creamy): The signature flavor for any monster cookie—choose creamy for the best texture.
Quick oats: Gives the cookie dough its hearty, chewy charm.
Mini chocolate chips: Doubles down on the chocolate in the cookie layer—tiny but mighty!
Mini M&M’s: For that authentic monster cookie look, vibrant crunch, and pops of sweetness.

How to Make Monster Cookie Fudgy Brownies

Step 1: Mix the Dry Cookie Ingredients

Start by grabbing a medium bowl and whisking together the all-purpose flour, cornstarch, baking soda, baking powder, and salt for the cookie dough layer. This step ensures your cookie topping bakes up tender and just a little puffy. Mixing these ingredients ahead gives you even distribution and guarantees every bite is balanced.

Step 2: Beat Butter and Sugars

In a stand mixer or with a hand mixer, whip the room-temperature butter with both the brown and white sugars. Cream them together for one full minute on medium speed—you want it light, creamy, and fluffy. This beating step incorporates air, making for a soft and chewy monster cookie top.

Step 3: Add Peanut Butter, Egg, and Vanilla

Now mix in the creamy peanut butter, beating for another minute until everything is silky smooth. Pour in the vanilla extract and egg, mixing just until combined. Scrape down the bowl to make sure nothing’s left behind, then give it all a quick mix to pull it together. You should end up with a thick, luscious cookie dough base.

Step 4: Combine Wet and Dry Cookie Mixtures, Add Goodies, and Chill

Blend your dry ingredients into the wet mixture gently—just until you don’t see streaks of flour. Then stir in the quick oats, mini chocolate chips, and mini M&M’s by hand for a rainbow-studded dough that screams “monster cookie!” Cover and chill for 40 minutes; this helps the flavors meld and the dough hold its shape once baked atop your brownies.

Step 5: Mix the Brownie Dry Ingredients

While your cookie dough chills, move on to the brownies. Whisk together all-purpose flour, Dutch-process cocoa, cornstarch, and salt in a medium bowl. This creates your ultra-chocolatey base, and that touch of cornstarch gives you a famously fudgy texture.

Step 6: Beat Eggs and Sugar for the Brownies

Add the sugar, eggs, and an extra egg yolk to your mixer with a whisk attachment and beat for a solid five minutes. The mixture will look pale, thick, and almost doubled in volume. This step is key for getting that crinkly brownie top we all crave! While it whips, melt your butter and let it cool slightly so it doesn’t scramble the eggs.

Step 7: Bring the Brownie Batter Together

With the mixer on low, slowly add in your melted butter, oil, and vanilla extract. Remove the bowl and gently fold in your dry brownie mix with a rubber spatula—be careful not to deflate all that airy goodness you just whipped in. Stir in both the semi-sweet and milk chocolate chips for maximum gooeyness.

Step 8: Layer and Bake the Monster Cookie Fudgy Brownies

Pour your brownie batter into a 9×9 pan lined with parchment—don’t skip the lining, you’ll thank yourself later! Spread into the corners, then bake for 15 minutes so the brownie top starts to set. While that’s in the oven, flatten golf ball-sized bits of chilled monster cookie dough into discs. Gently lay those dough pieces all over the top of the brownie batter when it comes out, creating a patchwork of cookie goodness. Return the pan to the oven, cover loosely with foil if needed to prevent over-browning, and bake for 25-30 minutes more. The finished bars should be just set, without any jiggle.

Step 9: Cool and Slice

Patience is a virtue here! Let the Monster Cookie Fudgy Brownies cool completely in the pan before you even think about slicing. The cooling process solidifies the fudgy center and ensures clean, gorgeous squares when you finally dive in.

How to Serve Monster Cookie Fudgy Brownies

Garnishes

Monster Cookie Fudgy Brownies are eye-catching as-is, but you can sprinkle a few extra mini M&M’s or chocolate chips over the top right after baking for that fresh-baked, bakery-style look. A pinch of flaky salt on the warm cookie layer can push the flavors over the edge (in the best way possible) and add a gourmet touch.

Side Dishes

Serve these brownies with a big scoop of vanilla bean ice cream for a classic hot-and-cold dessert pairing. Fresh berries, especially strawberries or raspberries, add a tart contrast that enhances all that rich chocolate and peanut butter. For parties, a tall glass of cold milk or a coffee bar nearby can turn these bars into a can’t-miss dessert centerpiece.

Creative Ways to Present

Try cutting the Monster Cookie Fudgy Brownies into bite-sized squares and arranging them on a dessert platter for parties or potlucks—they’ll go fast! Stack pieces in clear treat bags with a ribbon for homemade gifts. For a decadent sundae, nestle a warm square beneath scoops of ice cream, caramel sauce, and even more mini candies.

Make Ahead and Storage

Storing Leftovers

Keep any leftover Monster Cookie Fudgy Brownies tightly covered at room temperature for up to four days. The texture actually improves on day two as the flavors meld, making these even more irresistible in your lunchbox or as a late-night snack.

Freezing

These brownies freeze beautifully! Once completely cooled, cut them into squares and wrap individually in plastic wrap, then stash in an airtight container or zip-top bag. They’ll stay fresh for up to three months. Just thaw at room temperature before enjoying, or eat straight from the freezer for a firm, candy-bar-like texture.

Reheating

For that just-baked magic, pop a brownie square in the microwave for 10-15 seconds to warm it slightly. This softens the chocolate chips and brings back all that gooey fudginess. A quick reheat is perfect for pairing with ice cream or a drizzle of chocolate sauce!

FAQs

Can I use natural peanut butter instead of creamy?

Creamy peanut butter works best for the classic monster cookie texture, but if you use natural peanut butter, opt for a no-stir variety. Just be aware that the dough may be a bit softer and the cookies could spread more during baking.

Can I double this recipe?

Absolutely! Double all the ingredients and bake in a 9×13-inch pan. You may need to extend baking time by about 5-10 minutes; just keep an eye out for that set center and no jiggle in the batter.

What’s the secret to fudgy brownies?

For super fudgy brownies, don’t overbake—take them out when a few moist crumbs stick to a toothpick. The combo of extra yolk, cornstarch, and proper mixing all contribute to that dense, rich texture in the Monster Cookie Fudgy Brownies.

Can I swap in different mix-ins?

Definitely! Customize your cookie layer with chopped nuts, different flavored chips, or seasonal candies (think Reese’s Pieces or festive-colored M&M’s). Just keep the total mix-in amount about the same so the dough holds together nicely.

Why do I have to let the brownies cool completely?

It’s worth the wait! Cutting while hot leads to a gooey mess and uneven squares. Letting Monster Cookie Fudgy Brownies cool ensures tidy slices and perfect chewy-meets-fudgy texture in every bite.

Final Thoughts

Don’t let the extra steps scare you—Monster Cookie Fudgy Brownies are absolutely worth the effort, and every batch is an instant crowd-pleaser. Grab your favorite apron, crank up some music, and treat yourself (and your loved ones!) to a dessert that marries comfort and celebration in every bite. Give them a try and watch them disappear!

Monster Cookie Fudgy Brownies Recipe

★★★★★

5.2 from 11 reviews

Author: Ella
Total Time: 1 hour 15 minutes
Yield: 16 brownies 1x
Diet: Vegetarian

Print Recipe

Description

Indulge in the ultimate dessert mashup with these Monster Cookie Fudgy Brownies. Decadent fudgy brownies topped with monster cookie dough, filled with chocolate chips, M&M’s, and oats, creating a rich and chewy treat.

Instructions

Monster Cookies – In a medium-sized mixing bowl, mix together flour, cornstarch, baking soda, baking powder, and salt.
Mix – Using a mixer, beat the butter, brown sugar, and sugar together for 1 minute on medium. Add in the peanut butter and mix for another minute.
Mix – Add in the vanilla and egg. Mix until combined. Slowly add the dry ingredients, then add oats, M&M’s, and chocolate chips. Chill for 40 minutes.
Brownies – Preheat oven to 325F. Spray a 9X9 pan with non-stick spray. Line with parchment paper.
Mix – Whisk flour, cocoa powder, cornstarch, and salt. Beat sugar, eggs, and egg yolk. Add melted butter, oil, and vanilla. Fold in dry ingredients, then add chocolate chips.
Bake – Bake brownies for 15 minutes, then top with cookie dough discs. Bake for an additional 20 minutes, then cover with foil and bake for another 5-10 minutes until set. Cool completely before cutting.

Notes

You can customize the mix-ins for the monster cookie dough to suit your preferences.
Ensure the brownies are fully cooled before cutting to get clean slices.

Prep Time: 30 minutes
Cook Time: 45 minutes
Category: Dessert
Method: Baking
Cuisine: American