Go Back
–+ servings
Cosmic brownie-inspired chocolate cake topped with rainbow candy-coated chocolates and drippy ganache on a wooden cake stand.

Cosmic Brownie Cake

Amelia
This Cosmic Brownie Cake transforms the nostalgic Little Debbie treat into a rich, fudgy layer cake with chocolate ganache and colorful rainbow chips. Perfect for birthdays, parties, or when you're craving something deeply chocolaty and fun.
No ratings yet
Print Recipe Pin Recipe
Prep Time 30 minutes
Cook Time 30 minutes
Chill Time 30 minutes
Total Time 1 hour 30 minutes
Course Dessert
Cuisine American
Servings 12 Servings
Calories 520 kcal

Equipment

Ingredients
  

For the Cake Layers:

  • ¾ cups all-purpose flour
  • ¾ cup unsweetened cocoa powder
  • ½ tsp baking powder
  • ½ tsp baking soda
  • 1 tsp salt
  • 1 cup buttermilk
  • ½ cup brewed coffee or hot water
  • ¾ cup vegetable oil
  • 1 cup granulated sugar
  • ¾ cup brown sugar
  • 3 large eggs
  • 2 tsp vanilla extract

For the Chocolate Ganache Frosting:

  • 1 ½ cups semi-sweet chocolate chips
  • ¾ cup heavy cream
  • 1 tbsp unsalted butter

For Topping:

  • ⅓ cup rainbow candy-coated chocolate chips or chopped Cosmic Brownies

Instructions
 

Preheat Oven

  • Preheat your oven to 350°F (175°C). Grease and line two 8-inch cake pans with parchment paper.

Mix Dry Ingredients

  • In a bowl, whisk together flour, cocoa powder, baking powder, baking soda, and salt.

Mix Wet Ingredients

  • In a separate large bowl, combine buttermilk, coffee, oil, granulated sugar, brown sugar, eggs, and vanilla.

Combine

  • Slowly add the dry mixture to the wet mixture, stirring until smooth.

Bake

  • Divide the batter evenly between the prepared pans. Bake for 25–30 minutes or until a toothpick comes out with a few moist crumbs. Cool completely.

Make Ganache

  • Heat heavy cream until just simmering. Pour over chocolate chips and let sit for 2–3 minutes. Stir until smooth. Mix in butter. Let ganache cool until spreadable.

Assemble

  • Place one cake layer on a plate. Spread ganache over the top. Add the second layer and frost the top and sides with ganache.

Decorate

  • While the ganache is still soft, top with rainbow chips or chopped Cosmic Brownies.

Chill & Serve

  • Chill for 30 minutes to firm up. Slice and enjoy!

Notes

The coffee enhances the chocolate flavor but won’t make the cake taste like coffee.
Chill cake layers before assembling to avoid crumbs in the frosting.
For extra ganache, double the frosting portion.

Nutrition

Calories: 520kcalCarbohydrates: 62gProtein: 6gFat: 30gSaturated Fat: 14gCholesterol: 80mgSodium: 300mgFiber: 3gSugar: 44g
Keyword cosmic brownie cake
Tried this recipe?Let us know how it was!