These homemade Cosmic Brownies feature a thick and chewy brownie topped with rich fudge ganache and colorful rainbow chips.

homemade Cosmic Brownies stacked on a plate.

Copycat Cosmic Brownies Recipe

Little Debbie Cosmic Brownies were my favorite treat growing up. No joke… I packed a Cosmic Brownie in my school lunch every single day all the way until I graduated high school.

See, I already loved the the Little Debbie brownies, you know, the ones with nuts on top. I’m not a huge fan of nuts in my brownies, so when they introduced cosmic brownies, with their rainbow chocolate sprinkles on top, I switched and never looked back.

This is a fun recipe to make at home for parties – what a nostalgic treat!

Related: For another fun brownie recipe, try our Pecan Pie Brownies too!

close up of a Cosmic Brownie with a bite taken.

Ingredients

For your convenience, I’ve provided shop-able ad links to some of the ingredients and kitchen supplies used to make our cosmic brownies; read our disclosure policy here.

For the Brownies:

1 1/4 cups flour
3/4 cup unsweetened cocoa powder
1 cup sugar
2/3 cup packed brown sugar
1 1/2 sticks unsalted butter (melted)
2 large eggs (room temp)
3 Tablespoons milk
1/2 teaspoon baking powder
1 Tablespoons cornstarch
pinch salt
2 teaspoons vanilla

For the Frosting:

3/4 cup heavy whipping cream
1 cup semi sweet chocolate chips
Rainbow Chips

Kitchen Tools Used:

Non-slip mixing bowls
Medium saucepan
Wire whisk
9×13″ baking pan (This one comes with a handy lid!)
Parchment paper

Instructions

Brownie Directions:

To Prep: Preheat oven to 350°F and line a 9×13″ baking dish with parchment paper. Mist with baking spray and set aside.

Beat melted butter, sugars, and vanilla in a large bowl using an electric mixer or stand mixer. Add eggs, one at a time, continuing to mix until well incorporated.
In a separate mixing bowl, whisk together flour, cocoa powder, baking powder, cornstarch, and salt.
Gradually add the flour mixture to your batter, mixing on low speed. Alternate adding flour and milk, until everything is combined. The batter should be thick.
Scoop batter into your baking pan and spread with a spatula as evenly as possible. Bake at 350°F for 18-25 minutes, taking care not to overcook. Remove from oven and allow to cool in the pan.

Frosting Directions:

Heat the heavy whipping cream in a saucepan, until simmering (but not boiling). Remove from heat and add chocolate chips. Let the chocolate chips sit in the hot cream for a minute or two, then whisk until completely melted and smooth.
Pour the chocolate ganache over the top of the brownies and smooth with a spatula.
Sprinkle rainbow chips over the top of the brownies, while the frosting is still wet.
Allow to set, then slice and enjoy!

Video Demo:

Prep Tips

Pan Size – We’ve baked these in both a 9×13 inch rectangle pan and a 9×9 inch square pan. The rectangle pan makes thinner brownies, much like the store-bought kind. Using a square pan will make thicker brownies, but may require a couple extra minutes of baking time. Use a toothpick to check for doneness.

More of our favorite brownie recipes:

homemade Cosmic brownies on a plate, with one missing a bite.

Cosmic Brownies Recipe (Printable Recipe Card):

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5 from 1 vote

Homemade Cosmic Brownies

These homemade Cosmic Brownies feature a thick and chewy brownie topped with rich fudge ganache and colorful rainbow chips.

Prep Time10

Cook Time4 20

Total Time30

Course: Dessert

Cuisine: American

Keyword: brownies, chocolate, copycat

Servings: servings

Calories: 214kcal

Author: Stacey aka the Soccer Mom

Cost: $12

Equipment

9×13 inch pan
Parchment paper
Mixing bowls