Chaos Cake M&M Brownie Slab (Print Version)

Fudgy brownie slab loaded with M&Ms, chocolate chunks, and marshmallow for a festive holiday indulgence.

# Components:

→ Brownie Base

01 - 1 cup unsalted butter, melted
02 - 1 1/4 cups granulated sugar
03 - 3/4 cup light brown sugar, packed
04 - 3 large eggs
05 - 2 teaspoons vanilla extract
06 - 1 cup all-purpose flour
07 - 1 cup unsweetened cocoa powder
08 - 1/2 teaspoon salt

→ Mix-Ins & Topping

09 - 1 cup M&Ms, divided
10 - 1 cup semisweet chocolate chunks, divided
11 - 1/2 cup mini marshmallows
12 - 1/4 cup chopped walnuts or pecans (optional)
13 - 2 tablespoons festive sprinkles (optional)

# Directions:

01 - Preheat oven to 350°F (175°C). Line a 9x13-inch baking pan with parchment paper, ensuring an overhang for easy removal.
02 - In a large mixing bowl, whisk together melted butter, granulated sugar, and brown sugar until well combined and smooth.
03 - Beat in the eggs one at a time until fully incorporated, then stir in the vanilla extract.
04 - Sift the flour, cocoa powder, and salt into the wet ingredients. Gently fold until just combined, taking care not to overmix.
05 - Gently fold in half of the M&Ms and half of the chocolate chunks into the batter.
06 - Pour and spread the batter evenly into the prepared baking pan.
07 - Distribute the remaining M&Ms, chocolate chunks, mini marshmallows, and optional nuts evenly over the batter. Use a knife to gently swirl the toppings for a marbled effect.
08 - Bake for 28–32 minutes, or until the center is set but retains a fudgy texture. Avoid overbaking.
09 - Remove the pan from the oven. Sprinkle with festive sprinkles. Allow the slab to cool completely in the pan before lifting and slicing into desired portions.

# Expert Advice:

01 -
  • Uses simple pantry staples you likely already have
  • Comes together in just 20 minutes of prep time
  • Creates an impressive dessert with minimal effort
  • Customizable with whatever mix-ins you have on hand
  • Perfect balance of fudgy and crunchy textures
02 -
  • These brownies actually taste better the next day as the flavors meld
  • The recipe is extremely forgiving and perfect for baking with kids
  • Can be made up to 3 days ahead and stored in an airtight container
  • The contrasting textures make this far more interesting than regular brownies
03 -
  • The key to fudgy brownies is not overmixing the batter once the flour is added
  • For a more sophisticated flavor, add 1/2 teaspoon of espresso powder to the dry ingredients
  • Line your pan with parchment paper that extends over the edges for easy removal
  • Use a plastic knife to cut through the marshmallows without sticking