Cosmic Brownies

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5 from 8 votes
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If you like Little Debbie Cosmic Brownies you will love this homemade cosmic brownie recipe. The frosted brownies are ultra-rich and fudgy, and topped with rainbow chips, just like the original.

For another delicious copycat recipe check out these homemade oatmeal creme pies.

Homemade Cosmic Brownies

If you are a huge fan of brownies like I am, you are going to love this copycat cosmic brownie recipe. For more homemade brownie recipes try one-bowl brownies and s’mores brownies.

Copycat Cosmic Brownies

There is something wonderful and nostalgic about cosmic brownies, right?!

The bright and colorful brownies remind me of my childhood and birthday parties with friends.

Speaking of birthday parties, these fudgy brownies are really perfect for birthdays and other celebrations. The colorful rainbow chips give them a fun party vibe.

Copycat Cosmic Brownies

Cosmic Brownie Ingredients

  • Butter
  • Sugar
  • Brown sugar
  • Vanilla
  • Egg
  • Flour
  • Cocoa powder
  • Cornstarch
  • Baking powder
  • Salt
  • Whole milk
  • Heavy cream
  • Semi-sweet chocolate chips
  • Rainbow chips

How to Make Cosmic Brownies

  1. Mix Brownie Batter | Prepare your brownie batter as directed in the recipe card below. Once ready, pour the batter into your prepared pan.
  2. Bake | Bake for 20-25 minutes or until set. Do not overbake!
  3. Frost | Prepare chocolate ganache using chocolate chips and heavy cream. Frost cooled brownies and top with rainbow chips.

Cosmic Brownies Recipe

Tips For Making Cosmic Brownies

  • Looking for a shortcut? Use a boxed fudge brownie mix from the brownie base.
  • The rainbow candy-coated chips can be found at most mass retail grocery stores or ordered on Amazon here.
  • Slice your homemade cosmic brownies as large or small as you would like.
  • The cornstarch in this recipe helps to keep brownies moist and fudge-like.

Can I use store-bought frosting?

As you can see I made a homemade frosting for these cosmic brownies. I find it gives that ganache style texture from the classic Cosmic Brownie. If you do not want to make it, you can use chocolate frosting from the store. Just know it will alter the flavor of the brownies a bit.

How long do Cosmic Brownies last?

I find that storing them in the refrigerator helps to extend the shelf life of these frosted brownies. They will keep for up to a week in the fridge or three days if stored at room temperature.

If you don’t plan on eating them all right away, you can freeze your brownies for up to three months. Thaw in the refrigerator overnight then enjoy.

What is the secret to making good brownies?

One of the biggest things I can recommend is making sure you measure your ingredients properly and be careful to not overbake the brownies.

Those two steps, as simple as they sound, can be the reason you end up with dense or overcooked brownies.

More Tasty Brownies and Cookie Bars

Copycat Cosmic Brownies
5 from 8 votes

Cosmic Brownies

Author: Jaclyn
Prep: 10 minutes
Cook: 20 minutes
Total: 30 minutes
If you like Little Debbie Cosmic Brownies you will love this homemade cosmic brownie recipe. The frosted brownies are ultra-rich and fudgy, and topped with rainbow sprinkles, just like the original. 


Brownie Ingredients:

  • ¾ cups unsalted butter 1 ½ sticks, melted
  • 1 cup granulated sugar
  • cups brown sugar packed
  • 2 teaspoons vanilla extract
  • 2 large eggs room temperature
  • 1 ¼ cups all-purpose flour
  • ¾ cups unsweetened cocoa powder
  • 1 Tablespoon cornstarch
  • ½ teaspoons baking powder
  • ¼ teaspoon salt
  • 3 Tablespoons whole milk

Frosting Ingredients:

  • ¾ cups heavy whipping cream
  • 1 cup semi-sweet chocolate chips
  • rainbow chips


For the brownies:

  • Preheat oven to 350 degrees. Line a 9 x 13 inch baking dish with parchment paper and lightly spray with nonstick baking spray. Set aside.
  • In a large bowl, beat to combine melted butter, white sugar, brown sugar, and vanilla using an electric mixer. Add eggs, one at a time, mixing until well blended.
  • In a medium bowl, whisk to combine flour, cocoa powder, cornstarch, baking powder, and salt.
  • Slowly add the flour mixture to the wet ingredients while alternating adding in the milk. Mix just until combined.
  • Using a rubber spatula, spread the thick batter evenly into the prepared pan.
  • Bake at 350 degrees for 20-25 minutes.
  • Remove from oven and set aside to cool.

For the Frosting:

  • In a small pot, bring the heavy whipping cream to a slow simmer. Stir in the chocolate chips. Allow to sit for 1 minute, then whisk until smooth.
  • Pour over cooled brownies and spread into an even layer. Sprinkle immediately with rainbow chips.
  • Refrigerate for 1-2 hours until frosting is set. Lift parchment to remove brownies from pan. Slice and enjoy!


The brownies will keep for up to three days at room temperature or up to one week when stored in the fridge.
Copycat Cosmic Brownies

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Homemade Cosmic Brownies

5 from 8 votes (8 ratings without comment)

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