M&M Brookies (Brownie Cookies)

M&M brookie bars stacked on a piece of parchment paper.

These layered bars feature an incredible combination of brownies and M&M cookies! The brownie layer is moist and fudgy and the cookie layer is studded with colorful M&Ms and chocolate chips. A fun and festive treat that's the best of both worlds!

Course Dessert

Cuisine Dessert

Prep Time 30

Cook Time 33

Total Time 1 3

Servings

Calories 467kcal

Author Allison Mattina

Ingredients

Cookie layer:

1½ cups (188g) all purpose flour spooned and leveled or weighed
½ teaspoon baking powder
¼ teaspoon salt
½ cup (113g) unsalted butter softened
½ cup (100g) granulated sugar
⅓ cup (70g) light brown sugar packed
1 large egg
1 teaspoon pure vanilla extract
½ cup (84g) mini M&M's plus a few more for topping
⅓ cup (55g) chocolate chips plus a few more for topping

Brownie layer:

½ cup unsalted butter cut into eight pieces
1 cup (220g) light brown sugar packed
2 large eggs
1 teaspoon pure vanilla extract
½ cup (63g) all purpose flour spooned and leveled or weighed
⅓ cup (35g) unsweetened cocoa powder
½ teaspoon salt
1 teaspoon cornstarch
½ cup (85g) chocolate chips

Instructions

Cookie layer:

Preheat oven to 350°F with a rack in the center of the oven. Line a 9x9* square baking pan (preferably metal) with parchment paper and lightly grease it with nonstick spray. Set aside.
Whisk together flour**, baking powder, and salt. Set aside.
Using a hand mixer or stand mixer fitted with the paddle attachment, beat butter and both sugars for 1-2 minutes, until light and fluffy. Add egg and vanilla extract, mixing until combined and scraping the sides of the bowl as needed. On low speed, add in flour mixture and mix until just combined.
Gently stir in M&M's and chocolate chips. Place the cookie dough in the refrigerator while you assemble the brownie batter (this quick chill time makes it easier to work with).

Brownie layer:

Place the butter and brown sugar in a large microwave safe bowl. Microwave in 30 seconds increments, stirring between, until the butter is melted (about a minute). Whisk the hot melted butter and brown sugar until combined. Set aside to cool for 5 minutes. While it's cooling, in a separate bowl, combine the flour**, cocoa powder, salt, and cornstarch.
After 5 minutes, whisk eggs and vanilla into the melted butter/brown sugar. Add the dry ingredients and whisk until well combined. Tap the excess batter off the whisk and remove it from the bowl. Stir in the chocolate chips, scraping the sides and bottom of the bowl as necessary.

Assembly:

Remove about ½ cup brownie batter and set it aside. Pour the remaining brownie batter into the prepared pan and spread into an even layer. Note: if the parchment paper is moving around you can secure it in place with small binder clips - just be sure to remove the clips before baking.
Take the M&M cookie dough out of the fridge. Grab pieces of dough and press them into flat, irregular shaped pieces. Place the cookie dough all over the top of the brownie batter. The cookie dough will mostly cover the brownie batter. Spoon the reserved brownie batter over the top of the cookie dough in random spots (this gives a marbled effect). Press some additional M&M's and chocolate chips over the top (this makes for a prettier presentation).
Bake for 30-35 minutes. Start checking around 28 minutes and if the cookie dough is getting brown you can loosely tent it with foil. The bars are done when a toothpick inserted into the center comes out with moist or fudgy crumbs but no thin raw batter (if you hit a melted chocolate chip try again in another spot). The very center of the bars will be slightly underbaked when you remove them from the oven but they will firm up as they cool. Place the pan on a wire rack to cool completely.

Notes

*Pan size:

This recipe should be made in a 9x9 baking pan. It will be too much batter to squeeze into an 8x8. A metal baking pan conducts heat the best and it is my preferred choice for brownies and bars. I recommend a pan like this (affiliate link).

**Flour:

Flour should be weighed or measured by spooning the flour into your measuring cup and leveling it off. If you scoop your measuring cup directly into the flour it will be over-measured and will affect the texture of these bars.

Serving and storage:

Serve at room temp or slightly warm. They'll be more soft and gooey when warm. Store at room temp for up to two days or refrigerated for up to three days.

Nutrition