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Better Than Store-Bought Copycat Cosmic Brownies: Ultra Fudgy Recipe

Close-up of a fudgy cosmic brownie square topped with thick chocolate glaze and vibrant candy-coated chocolates.

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Make the best homemade Cosmic Brownies that deliver the nostalgic, dense, and fudgy texture of the classic treat, topped with smooth chocolate ganache and colorful rainbow chips. This from-scratch recipe beats any box mix.

Ingredients

Scale
  • 1 cup (2 sticks) unsalted butter
  • 1 1/2 cups granulated sugar
  • 1 cup packed light brown sugar
  • 4 large eggs
  • 1 tablespoon vanilla extract
  • 1 cup all-purpose flour
  • 3/4 cup unsweetened cocoa powder
  • 1/2 teaspoon salt
  • 1/4 teaspoon baking powder
  • 1/2 cup semi-sweet chocolate chips (for the batter)
  • 1 cup powdered sugar (for frosting)
  • 1/4 cup unsweetened cocoa powder (for frosting)
  • 1/4 cup milk or heavy cream (for frosting)
  • 1 teaspoon vanilla extract (for frosting)
  • 1/4 cup candy-coated chocolate chips (rainbow chips, for topping)

Instructions

  1. Preheat your oven to 350°F (175°C). Line a 9×13 inch baking pan with parchment paper, leaving an overhang on the sides for easy removal.
  2. In a large saucepan over medium heat, melt the butter. Remove from heat and whisk in the granulated sugar and brown sugar until fully combined.
  3. Whisk in the eggs one at a time until the mixture is smooth and glossy. Stir in the vanilla extract.
  4. In a separate bowl, whisk together the flour, cocoa powder, salt, and baking powder.
  5. Gradually add the dry ingredients to the wet ingredients, mixing just until combined. Do not overmix. Fold in the 1/2 cup of chocolate chips for the batter.
  6. Spread the batter evenly into the prepared baking pan.
  7. Bake for 25 to 30 minutes. A toothpick inserted near the center should come out with moist crumbs attached, not wet batter, for the fudgiest texture.
  8. Let the brownies cool completely in the pan on a wire rack. This is crucial before frosting.
  9. Prepare the ganache frosting: In a medium bowl, whisk together the powdered sugar and 1/4 cup cocoa powder.
  10. In a small saucepan, heat the milk or cream until just simmering. Remove from heat and whisk in the vanilla extract.
  11. Slowly pour the warm milk mixture into the dry frosting ingredients while whisking constantly until the frosting is smooth and thick. If it is too thick, add milk 1 teaspoon at a time.
  12. Once the brownies are completely cool, spread the chocolate ganache evenly over the top.
  13. Immediately sprinkle the candy-coated chocolate chips over the wet frosting.
  14. Allow the frosting to set for about 30 minutes before lifting the brownies out using the parchment paper overhang and cutting them into squares.

Notes

  • For an intensely rich flavor, use high-quality cocoa powder in both the batter and the frosting.
  • To achieve the signature dense texture, avoid overbaking; the center should remain slightly underdone when tested.
  • If you prefer a thicker layer of frosting, double the frosting recipe ingredients.

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