Homemade Cosmic Brownies

Fudgy, chocolatey, and adorable, these cosmic brownies are ten times better than store-bought.

By
Kayla Hoang
Kayla Hoang
Kayla Hoang
Kayla Hoang is a freelance recipe developer, writer, and baker. Her journey in food media began with interning at Martha Stewart Living Omnimedia and continued through Food Network, Kitchn, and freelance work.
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Updated January 19, 2024
Kayla Hoang
Homemade Cosmic Brownies spread all over a counter

Simply Recipes / Mark Beahm

The first time I had a Cosmic Brownie was at the lunch table in elementary school. A classmate had one in her lunch almost every day and she gave me a piece to try. I was hooked after that first bite.

As I’ve gotten older, my taste has evolved but my yearning for nostalgia is steadfast. I find such joy in recreating the treats I loved as a kid, making small tweaks here and there to fit my “grown-up” palette. 

With that in mind, I present these: an upgraded, homemade version of a Cosmic Brownie. A rich, deeply fudgy, moist brownie is topped with a silky, decadent ganache and topped with the same colorful, bright sprinkles to channel the joy of the original. 

While this recipe has a couple of moving parts, I promise they’re easier to make than meets the eye and will delight anyone who’s lucky enough to eat one. Plus, they store well in the refrigerator, making them a wonderful make-ahead dessert for get-togethers. 

What are Cosmic Brownies?

Little Debbie’s Cosmic Brownies are inspired by cosmic bowling. Cosmic bowling (or glow bowling as I knew it growing up) is outer space-themed, glow-in-the-dark bowling. Think black lights, lasers, and lots of bright, neon colors against a dark bowling alley. The colorful sprinkles set against the dark chocolate color of the fudgy brownie mimics this iconic look.

Stack of Homemade Cosmic Brownies and more on the counter around it

Simply Recipes / Mark Beahm

Homemade for the Win

In preparing to develop this recipe, I bought a box of Cosmic Brownies for research. Before revisiting the store-bought version, I already knew I wanted these to be undeniably fudgy with a moist crumb. Upon re-tasting the store-bought version, I realized how crumbly yet sort of doughy the original is. I also never realized how un-chocolate-y they are. I knew I could do better.

Even though they’re convenient to grab a pack from the store, it’s 100% worth it to make these from scratch. Using a combination of Dutch-process cocoa powder and melted bittersweet chocolate ensures these brownies are undeniably chocolatey. Moreover, the brownies come out beautifully fudgy with a moist, soft crumb. 

Rather than topping the brownies with a thin layer of almost flavorless glaze, these are crowned with a quick ganache that looks beautiful and adds to the chocolatey goodness.

Tips and Tricks 

These brownies are super straightforward to make and come together easily, but here are some of my best tips to ensure they come out perfect every time:

  • Finely chopping the chocolate for the brownies and the ganache ensures it melts quickly and completely.
  • Whisking the sugars, eggs, and vanilla together helps to create a lighter, smoother brownie and also yields the coveted paper-thin, crinkly, shiny top that bakers love.
  • The brownies will likely puff around the 25-minute mark with a toothpick still coming out wet, then settle in the next couple minutes. Once the brownies settle, they are typically ready. You want a toothpick to come out with moist crumbs, not wet batter. 
  • The brownies will deflate slightly in the center as they cool, creating some dips and valleys, so feel free to flip the brownies over so that the even bottom is facing up before spreading the ganache. 
A stack of two homemade Cosmic Brownies on a plate with the top missing a bite

Simply Recipes / Mark Beahm

Easy Variations

At their core, even without the ganache topping and crunchy sprinkles, these are delicious fudgy brownies, ripe for adapting to whatever you’re craving. Consider these:

  • Skip the toppings altogether and serve the brownies warm with vanilla ice cream.
  • Fold nuts, such as pecans or walnuts, into the batter and swap the sprinkles for more toasted nuts.
  • Swap all of the bittersweet chocolate for semi-sweet if you like things on the sweet side or consider a combination of the two to fit your palette.
  • Can’t find the candy-coated chocolate chip sprinkles? Try mini M&Ms or swap in another of your favorite sprinkles.

Tips for Perfect-Looking Brownies

Cutting perfect-looking brownies doesn’t have to be complicated or involve crazy tools. You just need a little bit of patience and the right knife. When aiming for clean slices, letting your brownies cool completely is crucial. Additionally, if cutting brownies that are topped with ganache (like these), you want to make sure it’s set before cutting.

I think the true key to getting the cleanest cuts lies in the way you use your knife. While not always possible, it’s helpful to use a knife that is longer than the length of the brownies so that you can make a full cut without stopping and starting. Moreover, a hot, dry knife will always result in a cleaner slice. I like to run my knife under hot water, then wipe it dry with a clean towel between each cut.

Homemade Cosmic Brownies on the counter

Simply Recipes / Mark Beahm

How to Store

The brownies can be stored in a single layer in an airtight container at room temperature for up to 2 days. They also keep extremely well in an airtight container in the refrigerator for up to 1 week and can be eaten cold or at room temperature.

Nostalgic Dessert Recipes

Homemade Cosmic Brownies

Prep Time 20 mins
Cook Time 30 mins
Cool/Chill Time 90 mins
Total Time 2 hrs 20 mins
Servings 8 to 16 servings
Yield 1 8x8 pan

You can swap 5 ounces bittersweet chocolate chips (about 3/4 cup) for the chopped chocolate in the brownies and 3 ounces bittersweet chocolate chips (about a scant 1/2 cup) for the chopped chocolate in the ganache.

Ingredients

For the brownies

  • Nonstick cooking spray

  • 1/2 cup (113g) unsalted butter

  • 1/4 cup (28g) Dutch-process cocoa powder

  • 2 tablespoons neutral oil, such as canola or vegetable

  • 5 ounces (142g) bittersweet chocolate, finely chopped

  • 2/3 cup (145g) granulated sugar

  • 1/3 cup (72g) packed light brown sugar

  • 2 large eggs, at room temperature 

  • 1 teaspoon vanilla extract

  • 1/4 cup (32g) all-purpose flour

  • 1/2 teaspoon baking powder

  • 1/2 teaspoon kosher salt

For the ganache and topping

  • 3 ounces (85g) bittersweet chocolate, finely chopped

  • Pinch kosher salt

  • 6 tablespoons heavy cream

  • Candy-coated chocolate chip sprinkles, as desired for topping

Method

  1. Preheat the oven to 350°F.

    Place a rack in the middle of the oven and preheat. 

    Lightly spray an 8x8-inch square baking pan with nonstick cooking spray and line with a sheet of parchment that completely covers the bottom with a slight overhang on two sides. Lightly spray the pan once more, taking care to grease the parchment and sides.

    Parchment paper lined baking sheet for homemade Cosmic Brownies recipe

    Simply Recipes / Mark Beahm
  2. Make the chocolate mixture: 

    In a small saucepan, melt the butter over medium heat until just melted, swirling the pan as needed to avoid browning, 2 1/2 to 3 minutes. Remove from the heat. 

    Add the cocoa powder and oil to the hot butter and whisk to fully incorporate and bloom the cocoa. Add the chopped bittersweet chocolate and whisk until fully melted and combined. Set aside to cool slightly while you whisk the egg mixture.

    Pot of melted butter on a coaster for homemade Cosmic Brownie recipe

    Simply Recipes / Mark Beahm
    Chocolate pieces added to pot with a whisk for Cosmic Brownie recipe

    Simply Recipes / Mark Beahm
    Chocolate pieces whisked into the melted butter and cocoa mixture in the pot for homemade Cosmic Brownie recipe

    Simply Recipes / Mark Beahm
  3. Whisk the sugars, eggs, and vanilla together: 

    In a large bowl, vigorously whisk the granulated sugar, light brown sugar, eggs, and vanilla until lightened in color and well combined, about 2 minutes. 

    Scrape the chocolate mixture into the bowl with the egg mixture and whisk to combine.

    Sugar, eggs, and vanilla whisked together in a bowl

    Simply Recipes / Mark Beahm
    Chocolate mixture whisked into the egg mixture for homemade cosmic brownies recipe

    Simply Recipes / Mark Beahm
  4. Combine the dry ingredients and add to the batter:

    In a small bowl, whisk the flour, baking powder, and salt to combine. Add the flour mixture to the chocolate mixture and whisk until just combined. It’s okay if there are some flour streaks. Use a rubber spatula to give the batter a few good folds, taking care to scrape the bottom of the bowl to get all the dry ingredients, until all the flour is incorporated.

    Two bowls (L to R): bowl with dry ingredients and bowl of wet ingredients, each bowl has a whisk

    Simply Recipes / Mark Beahm
    Homemade cosmic brownie mixture folded together using a rubber spatula

    Simply Recipes / Mark Beahm
  5. Transfer the batter to the pan and bake:

    The brownie batter will be on the thicker side. Scrape the batter into the prepared pan and spread into an even layer using the spatula, a small offset spatula, or the back of a spoon. 

    Bake the brownies on the middle rack of the oven the top has a paper-thin crinkly appearance, and a toothpick comes out clean or with moist crumbs (not wet batter), 25 to 28 minutes. The brownies will likely puff around the 25-minute mark with a toothpick still coming out wet, then settle in the next couple minutes. Once the brownies settle, they are typically ready.

    Cool the brownies completely in their pan set over a wire rack, about 1 hour.

    Homemade Cosmic Brownie batter in a lined baking pan

    Simply Recipes / Mark Beahm
    Baking pan with homemade Cosmic Brownies on a cooling rack

    Simply Recipes / Mark Beahm
  6. Make the ganache: 

    Once the brownies are cool, make the ganache. Combine the chopped chocolate and pinch of salt in a small bowl or large glass measuring cup.

    In a small saucepan (you can rinse, dry, and reuse the same one from the brownies), heat the heavy cream over medium heat until it comes to a simmer with vigorous bubbling just around the edges and steam coming off the surface, 1 to 2 minutes. Immediately pour the hot cream over the chocolate, let sit for a minute, then stir until smooth and silky and all the chocolate is melted.

    Chocolate pieces in a bowl

    Simply Recipes / Mark Beahm
    Heavy cream added to bowl of chocolate for homemade Cosmic Brownie ganache

    Simply Recipes / Mark Beahm
    Bowl of ganache with a rubber spatula for homemade Cosmic Brownie ganache

    Simply Recipes / Mark Beahm
  7. Pour the ganache over the brownies: 

    Lift the brownies out of the pan by the parchment overhang and transfer to a cutting board. If desired, you can flip the brownies over so that the bottom is facing up for a very even surface to spread the ganache.

    While the ganache is still warm and spreadable, pour it over the brownies and use a small offset spatula or the back of a spoon to spread into an even layer. It’s okay if it doesn’t look completely smooth at first. The ganache will settle into itself. Try to avoid pushing the ganache over the sides. Top the ganache with the candy-coated chocolate chip sprinkles as desired.

    Offset spatula used to spread ganache on the brownie on a parchment paper

    Simply Recipes / Mark Beahm
    Ganache covered homemade Cosmic Brownie on a piece of parchment paper

    Simply Recipes / Mark Beahm
    Chocolate chip rainbow candy sprinkled on the homemade Cosmic Brownie and more in a bowl

    Simply Recipes / Mark Beahm
  8. Set, slice, and serve:

    Transfer the brownies to the refrigerator to chill until the ganache is set and firm enough to cut, about 30 minutes. Use a hot, dry knife (I like to run my knife under hot water and then wipe it dry with a clean towel) to cut the brownies, wiping the knife clean between each cut. 

    If cutting into bars and adding the signature perforated line, first cut the brownies down the center to create two long halves. Lightly drag the side of an offset spatula, back of a butter knife, or skewer in a straight line down the middle length of each half to create the signature look, taking care to not drag through all the way to the brownie. Then, cut each half into 4 pieces with the indentation running crosswise to yield 8 bars total. Alternatively, you can cut the brownies into 16 squares and skip the perforated line altogether. 

    The brownies can be stored in a single layer in an airtight container at room temperature for up to 2 days or chilled in the refrigerator for up to 1 week. 

    Love the recipe? Leave us stars and a comment below!

    Homemade Cosmic Brownies sliced into bars on a cutting board

    Simply Recipes / Mark Beahm
    Homemade Cosmic Brownies (with signature perforated line) on a piece of parchment paper

    Simply Recipes / Mark Beahm
    Homemade Cosmic Brownies spread all over a counter

    Simply Recipes / Mark Beahm
Nutrition Facts (per serving)
248 Calories
18g Fat
20g Carbs
3g Protein
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Nutrition Facts
Servings: 8 to 16
Amount per serving
Calories 248
% Daily Value*
Total Fat 18g 23%
Saturated Fat 10g 49%
Cholesterol 45mg 15%
Sodium 75mg 3%
Total Carbohydrate 20g 7%
Dietary Fiber 3g 9%
Total Sugars 14g
Protein 3g
Vitamin C 0mg 0%
Calcium 36mg 3%
Iron 3mg 16%
Potassium 142mg 3%
*The % Daily Value (DV) tells you how much a nutrient in a food serving contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.
Nutrition information is calculated using an ingredient database and should be considered an estimate. In cases where multiple ingredient alternatives are given, the first listed is calculated for nutrition. Garnishes and optional ingredients are not included.