Introduction

These Monster Cookie Fudgy Brownies combine rich, chocolatey brownie with classic monster cookie flavors for a decadent treat. Packed with chocolate chips, oats, and colorful M&M’s, they’re perfect for satisfying any sweet tooth.

A stack of rich, thick dessert bars is shown with about two layers each: the bottom layer is dark, fudgy chocolate with a moist texture, and the top layer is a lighter, golden cookie dough containing colorful candy-coated chocolate pieces and small chocolate chunks. The bars are cut into squares and piled unevenly on white parchment paper, placed on a round wooden board, with some candy pieces scattered around. The photo has a soft, bright background with a white marbled texture and a tied glass jar is slightly out of focus in the background. Photo taken with an iphone --ar 4:5 --v 7

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

Instructions

Step 1: In a medium bowl, mix together 1/2 cup flour, 1 tsp cornstarch, baking soda, baking powder, and 1/4 tsp salt for the cookie dough.
Step 2: Using a mixer, beat room temperature butter, brown sugar, and white sugar together on medium speed for 1 minute until light and fluffy. Add peanut butter and mix for another minute.
Step 3: Add vanilla extract and egg, mixing until combined. Scrape the bowl and mix for an additional 20 seconds.
Step 4: Slowly incorporate the dry ingredients into the wet until just combined. Fold in oats, mini M&M’s, and mini chocolate chips. Cover and chill the dough for 40 minutes.
Step 5: While the cookie dough chills, preheat the oven to 325°F. Prepare a 9×9-inch pan by spraying with non-stick baking spray and lining the bottom plus two sides with parchment paper.
Step 6: In a medium bowl, whisk together 1/2 cup flour, cocoa powder, 1 tbsp cornstarch, and 1/4 tsp salt for the brownie batter.
Step 7: Using a mixer with a whisk attachment, beat sugar, eggs, and egg yolk for 5 minutes until very light and fluffy. Meanwhile, melt 5 tbsp butter and let it cool slightly.
Step 8: Add melted butter, oil, and vanilla extract to the egg mixture and mix on low until combined. Carefully fold in dry ingredients using a rubber spatula, preserving the airiness.
Step 9: Fold in semi-sweet and milk chocolate chips. Pour the batter into the prepared pan and smooth into the corners with a spatula.
Step 10: Bake brownies for 15 minutes, allowing the top to set slightly before adding cookie dough.
Step 11: Remove cookie dough from fridge. Take small handfuls, flatten into discs, and arrange on top of partially baked brownies, covering evenly.
Step 12: Bake for another 20 minutes. Loosely cover with foil to prevent over-browning, then bake an additional 5–10 minutes until both the brownie and cookie layers are set with no jiggle.
Step 13: Remove from oven and place pan on a cooling rack. Let brownies cool completely to room temperature before cutting and serving.

Tips & Variations

Use parchment paper lining to easily lift the brownies out for clean slicing.
For a nuttier flavor, substitute crunchy peanut butter or add chopped nuts to the cookie dough.
Allowing the egg mixture to beat 5 minutes is key for a light, fudgy texture in the brownies.
Try swapping mini M&M’s with other colorful candies or chocolate chunks to customize flavors.

Storage

Store brownies at room temperature in an airtight container for up to 3 days. To keep longer, refrigerate for up to 5 days. Reheat briefly in a microwave to soften before serving.

How to Serve

The image shows a close-up of square dessert bars with two layers: a dark, rich, fudgy brownie base and a lighter, golden brown cookie dough top layer studded with small colorful candy-coated chocolates (red, yellow, blue, green, and orange) and chocolate chips. One bar is cut diagonally and slightly lifted, showing the thick, moist brownie layer beneath the soft, chewy cookie topping. The bars rest on crumpled parchment paper placed on a white marbled surface. Photo taken with an iphone --ar 4:5 --v 7

Serve this delicious recipe with your favorite sides.

FAQs

Can I use salted butter instead of unsalted?

Yes, but reduce or omit the added salt in the recipe to prevent the brownies and cookies from becoming too salty.

Can I make the cookie dough and brownie batter ahead of time?

Yes, you can prepare both mixtures in advance. Keep the cookie dough chilled until ready to use, and store the brownie batter in the refrigerator for up to 24 hours before baking.