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+ servings
Squares of rainbow chip topped cosmic brownies on a white parchment paper.

Cosmic Brownies

These homemade cosmic brownies are ultra rich and fudgy! Dare i say, WAY BETTER than the store bought version.
Course Dessert
Cuisine American
Prep Time 15 minutes
Cook Time 25 minutes
Total Time 40 minutes
Servings 24 brownies
Calories 215kcal



  • 8 oz semi-sweet chocolate chopped OR 1 1/4 cups chocolate chips
  • 1/2 cup heavy cream
  • pinch salt



  • Preheat oven to 350°F. Line a 13x9 with parchment paper, or with foil (then lightly spray with cooking spray if using foil). 
  • In the bowl of a stand mixer fitted with a paddle attachment, or using hand beaters, beat the melted butter, brown sugar, and sugar on medium speed for 2 minutes.  
  • Add the eggs and egg yolk, one at a time, beating well after each addition. Add the vanilla and mix again.
  •  In a small bowl whisk the flour, cocoa, cornstarch, and salt. 
  • Add the dry ingredients to the wet ingredients and mix until just combined. 
  • Spoon the batter into the prepared pan. Using a spatula, level the batter so that its in an even layer. 
  • Bake for 18-24 minutes. (don’t overbake or they will be dry. Mine baked for about 21 minutes).
  • Remove from the oven and let brownies cool in the pan. 
  • While cooling make the ganache. 


  • To make ganache, place the chopped chocolate or chocolate chips in a medium sized heat proof bowl. 
  • In a small saucepan over medium heat, warm the heavy cream. Bring to a simmer, once it’s almost boiling remove from heat and pour the heavy cream over the chopped chocolate. Add pinch of salt.
  •  Let the heavy cream sit over the chocolate for 3 minutes before stirring. *see notes
  • After 3 minutes, use a small whisk and slowly begin whisking the cream and chocolate, starting in the center of the bowl and slowly moving towards the edges. 
  • The ganache will get smooth. Once smooth, let the ganache sit for 5 minutes and then pour over the partially cooled brownies and spread using a spatula. 
  • Sprinkle with rainbow chips.
  • Allow ganache to set, about 2-3 hours, or you can place in fridge for 45 minutes to speed up the process. 


Brownie Tips:
Don’t over bake. The biggest culprit to dry brownies is over-baking them! All ovens vary. The brownies are done when a toothpick comes out with moist crumbs. 
Remove from the oven and let brownies cool in the pan. Note: they don’t need to be fully cooled before spreading the ganache overtop, but the brownies should be on the cooler side.
Be sure to whisk the dry ingredients together in a separate bowl. Since you have the cornstarch in there, you really want to make sure all the dry ingredients are incorporated evenly. This will help when mixing the dry ingredients into the wet ingredients for a more even dispersion of the cornstarch — resulting in a thick consistency across the entire pan.
Ganache Tips:
You can use 1 1/4 cups of chocolate chips OR finely chopped chocolate. I used chocolate chips because I always have them in my pantry. You can use a variation of chocolate with the ganache and do half milk chocolate and half semi-sweet chocolate chips.
Be sure to let the hot cream sit over the chocolate for at least 3 minutes. This waiting period lets the cream melt the chocolate while bringing down the temperature of the cream. If you whisk the cream and chocolate while the cream is still really hot (and fresh from the saucepan) it can cause the ganache to break which will result in a gritty texture.
I wouldn’t start making your ganache until a few minutes before your brownies are ready for the ganache. You don’t want your ganache to harden in the bowl while your brownies are still baking or are just out of the oven.


Calories: 215kcal | Carbohydrates: 26g | Protein: 2g | Fat: 12g | Saturated Fat: 7g | Cholesterol: 46mg | Sodium: 13mg | Potassium: 120mg | Fiber: 2g | Sugar: 19g | Vitamin A: 286IU | Calcium: 24mg | Iron: 1mg