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This homemade Cosmic Brownie recipe is a copycat version of Little Debbie’s famous treat. A chewy decadent brownie topped with a rich chocolate ganache and rainbow chips. If you liked the classic rainbow sprinkle brownies, you’ll love this upgraded version even more!

stack of two cosmic brownies with a bite missing from the top one.

Copycat Cosmic Brownies

My parents were never big on packaged desserts. I really don’t think I’ve had a Twinkie. But there is something so nostalgic about any of the snacks that come in those recognizable boxes.

I was always so intrigued by the little rainbow chips on Cosmic Brownies. They’re still so fun.

I can pretty confidently say that brownies are my favorite dessert. You’ve seen me make coconut oil brownies, better than box mix brownies, and Halloween cream cheese swirl brownies…just to name a few. So I can safely safe I am a pretty decent brownie critic.

When, as an adult, I had my first Cosmic Brownie, I was so disappointed. They taste a bit…cardboardish? This homemade version is 100% better, but still has the same nostalgic vibes.

They are nut-free and safe for school lunches and bake sales, they make a great afternoon snack with a cold glass of milk and of course perfect for an after-dinner dessert.

Why you’ll love this Cosmic Brownie recipe

Childhood Favorite – If you’ve enjoyed a Little Debbie Cosmic Brownie, you’ll love the homemade version even more.

Full of Chocolate Flavor – These fudgy brownies are full of melted chocolate and cocoa powder for maximum chocolate flavor.

Rainbow Candies – Those little rainbow candy-coated chocolate chips are so cute!

No Mixer – Brownies turn out best when you don’t overmix them with a hand mixer so just use a whisk and/or spatula for these & they’ll turn out even better.

side view of rainbow chip brownies.

Things you’ll need

Cosmic Brownie Ingredients

Below is a list of the ingredients you’ll need to gather to make this recipe. Scroll all the way down for the full recipe card.

  • Sugars – You’ll need a mix of both granulated white sugar and brown sugar.
  • Vanilla Extract – Pure vanilla extract (not imitation) for the best flavor. I buy it in bulk at Costco or Sam’s Club.
  • Salt – To balance the sweet.
  • Eggs – You’ll add two full eggs and two egg yolks. The extra egg yolk makes for an even richer brownie.
  • Butter – Salted or unsalted. I personally usually use salted.
  • Chocolate chips – I like to use Ghirardelli 60% baking chips but semi-sweet chocolate chips work fine if that’s what you prefer.
  • Rainbow Candies – You can find these on Amazon or at Hobby Lobby. Mini M&M candies will also work.
  • Vegetable Oil – The combo of melted butter and some oil makes for amazing texture.
  • Flour – I’ve only tested with all purpose flour.
  • Cocoa Powder – Unsweetened cocoa powder.
  • Heavy Cream – To make the chocolate ganache frosting, you’ll need heavy cream. Whole milk will also work, but you’ll need to add some butter. Or, I have a thinner frosting option listed in the recipe card, if you prefer.
overhead shot of ingredients laid out to make cosmic brownies

How to make Cosmic Brownies

This section shows you how to make this recipe, with process photos showing the steps to help you visualize it. For full instructions, including amounts and temperatures, see the recipe card below.

  1. STEP ONE: To a large mixing bowl, whisk together the sugars, vanilla, salt, eggs and yolks.
  2. STEP TWO: Add the butter and chocolate chips to microwave safe bowl and heat in 30 second intervals, stirring between each, until melted and smooth. Whisk in the vegetable oil.
  3. STEP THREE: Pour the cooled chocolate mixture into the sugar mixture and stir until combined. Then gently fold in the flour and cocoa until there are no traces of powder.
collage of mixing bowl making cosmic brownies
  1. STEP FOUR: Pour the brownie batter into a 9×13 baking dish that has been lined with parchment paper and bake in a 350°F preheated oven for 30 minutes or until a toothpick inserted in the middle comes out clean.
  2. STEP FIVE: To make the ganache, pour the heavy cream into a medium microwave safe bowl and heat for 1 minute. Pour the chocolate chips in and let them sit for 2-3 minutes. After sitting, stir until melted and smooth.
  3. STEP SIX: Pour the ganache onto the cooled brownies and spread into an even layer. Sprinkle on the rainbow chips and let set. Once set, slice and serve!

Let cool completely before slicing.

If you prefer a thinner frosting that sets as opposed to the thick chocolate ganache, try this:

  • 4 Tablespoons unsalted butter
  • 1/2 cup sweetened condensed milk
  • 8 ounces chocolate chips

To a medium microwave safe bowl, add the butter and sweetened condensed milk and heat for 30 seconds, stirring until smooth. Pour in the chocolate chips and stir until melted and smooth.

If using this frosting, the brownies can be stored in an airtight container at room temperature for up to 4 days.

Why are they called Cosmic Brownies?

The original Little Debbie’s snack version of these cosmic brownies were developed in the 60’s however there doesn’t seem to be much written on why they are called what they’re called.

One can only assume it’s because the colorful chocolate chips atop the dark chocolate brownie mimics the galaxy!

How to store them

With the cream based chocolate ganache topping, I prefer to store them covered in the fridge. They are best eaten within the first couple of days, but they’ll last up to 4 days.

They won’t last that long. Promise.

brownie topped with sprinkles with a bite missing.

Can I freeze them?

Yes, wrap the brownies individually and place in a freezer bag. They can be frozen for up to 3 months.

Move them to the fridge to thaw when you’re ready to enjoy them.

Where do I find rainbow chips?

Rainbow chips are unique in that they are chocolate chips that are candy-coated which gives them those fun colors!

They are not as easy to find as regular chocolate chips but Walmart and Hobby Lobby carries them.

Any bulk food/candy store should have them as well but if you are really having a hard time, you can always order online.

While you have them, make a Cosmic Brownie Pie, Cosmic Brownie Cookies and Cosmic Brownie Hot Chocolate Bombs while you’re at it.

Click here to view my entire collection of brownie recipes.

stack of homemade cosmic brownies.

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stack of two cosmic brownies with a bite missing from the top one.
4.95 from 17 votes

Homemade Cosmic Brownie Recipe

Servings: 18 brownies
Prep Time: 20 minutes
Cook Time: 30 minutes
Total Time: 50 minutes
This homemade Cosmic Brownie recipe is a copycat version of Little Debbie's famous treat. A chewy decadent brownie topped with a rich chocolate ganache and rainbow chips. If you liked the classic rainbow sprinkle brownies, you'll love this upgraded version even more!


For the Brownies

For the Chocolate Ganache


  • ¼ cup Rainbow Chocolate Chips


To make the brownies

  • Preheat the oven to 350°F. Line a 9×13 inch baking dish with parchment paper and spray with cooking spray. Set aside.
  • To a large bowl, add the granulated sugar, brown sugar, vanilla, salt, whole eggs and yolks and whisk until combined.
    1 cup granulated white sugar, 1 cup brown sugar, 2 teaspoons vanilla extract, 1/2 teaspoon salt, 2 large eggs, 2 large egg yolks
  • To a microwave safe bowl, add the butter and chocolate chips. Microwave for 30 seconds, stir, then microwave another 30 seconds and stir. Repeat until melted and smooth.
    8 Tablespoons unsalted butter, 8 ounces chocolate chips
  • Whisk in the vegetable oil to the melted chocolate.
    ½ cup vegetable oil
  • Pour the chocolate mixture into the sugar mixture and mix until fully combined. Gently fold in the flour and cocoa.
    1 ¼ cups all-purpose flour, ¼ cup unsweetened cocoa powder
  • Pour the brownie batter into the prepared pan and bake until a toothpick inserted in the center comes out clean, 30 to 35 minutes.

To make the ganache

  • Pour the heavy cream into a microwave safe bowl and heat for 1 minute.
    ½ cup heavy cream
  • Pour the chocolate chips into the heated cream and let stand for 2 minutes. After the time is up, stir until the chocolate is melted and smooth.
    1.5 cups chocolate chips
  • Pour the ganache over the brownies, spreading evenly with an offset spatula, and immediately sprinkle with the rainbow chips.
    ¼ cup Rainbow Chocolate Chips
  • Let cool completely before slicing.



  • I use and recommend Ghirardelli 60% baking chips in both the batter and the ganache.
  • Once set, slice into 12-18 brownies, depending on how generous you’d like to make them. 
  • Store leftovers covered in the fridge for up to 4 days.
  • For an alternate frosting that will set and not need to be chilled, use 4 Tablespoons unsalted butter, 1/2 cup sweetened condensed milk, and 8 ounces of chocolate chips. Heat in a microwave safe bowl and pour over the brownies. 


Serving: 1g | Calories: 357kcal | Carbohydrates: 51g | Protein: 4g | Fat: 16g | Saturated Fat: 10g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 2g | Trans Fat: 0.3g | Cholesterol: 66mg | Sodium: 99mg | Potassium: 69mg | Fiber: 1g | Sugar: 42g | Vitamin A: 372IU | Vitamin C: 0.2mg | Calcium: 58mg | Iron: 1mg

Nutritional information is an estimate and provided to you as a courtesy. You should calculate the nutritional information with the actual ingredients used in your recipe using your preferred nutrition calculator.

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Originally published July 26, 2020; photos and recipe updated February 1, 2024.

stack of chocolate brownies with rainbow sprinkles
overhead shot of three cosmic brownies

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