Back to school has me feeling all the feels for old school treats, these Cosmic Brownies being one of them. Let me be very clear, these copycat cosmic brownies are rich, ultra fudgy, and moist. Yep! Not a dry crumb can be found.

We take that perfectly dense brownie base and top it with a decadent and silky chocolate ganache. These beautiful chocolate treats put Little Debbies Cosmic Brownies to shame.

A Cosmic Brownie with a bite taken out of it.

I’ve been making some amazing desserts recently, Nutella Brownies have been really popular around here as have my brownie cookies.

But today we’re going to dive into these cosmic brownies. I couldn’t. Stop. Eating. Them.

And before we continue I have to point out the photo below because it illustrates just how dense and fudgy the brownie base truly is.

And the ganache!! It’s perfection. If you’ve struggled with ganache in the past, don’t fret because I’m sharing some great tips and tricks to get that perfect silky smooth chocolate ganache.

Cosmic brownies on a white parchment paper.

How to make Cosmic Brownies

Before you begin mixing the ingredients, preheat your oven to 350°F. Line a 13×9 inch pan with foil and lightly spray it with cooking spray OR use parchment paper. If you use parchment paper you don’t have to spritz it with cooking spray, but it doesn’t hurt to do so.

Make the Brownies

In the bowl of a stand mixer, or with hand beaters, beat the melted butter, brown sugar, and sugar on medium speed for 3 minutes.

Add the eggs and egg yolk, one at a time, beating well after each addition.

Add the vanilla and mix that in real nice.

Melted butter and brown sugar in a glass bowl, for making Cosmic Brownies.

In a small bowl whisk the flour, cocoa powder, cornstarch, and salt.

Add the dry ingredients to the wet ingredients and mix until just combined. The batter is quite thick!

Spoon the batter into the prepared pan. Using a spatula level the batter so that its in an even layer.

Thick cosmic brownie batter in a glass bowl.

Bake for 20-25 minutes.

Pro tip: Don’t over bake. The biggest culprit to dry brownies… over baking them!

I can guarantee your oven and mine vary. I have an oven thermometer in my oven at all times; but just remember to check the brownies periodically. K, thanks!

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.

Chocolate chips and heavy cream in a bowl for making ganache.

Make the Cosmic Brownie Ganache

Ingredients needed to make the ganache:

  1. Semi-sweet chocolate
  2. Heavy cream
  3. Pinch of salt – not absolutely necessary, it’s just a bit of contrast to the chocolate, so omit it if you must. No one will be able to tell.

Pro tip: 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.

Ganache Bonus tip: I’ve seen others use a variation of chocolate with their ganache; some do half milk chocolate and half semi-sweet. You can definitely do this. But I have to make a disclaimer and say I’ve never done this before so I’m not sure if it turns out as great.

A whisk in a bowl full of chocolate ganache.

How to make smooth 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 chocolate. Add pinch of salt.

Let the heavy cream sit over the chocolate for 3 minutes before stirring.

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 4-5 minutes and then pour it over the brownies and spread it into an even layer with a spatula.

Sprinkle with rainbow chips.

Allow ganache to set, about 2-3 hours, or you can place the brownies in the fridge for 30-45 minutes to speed up the setting process.

Cosmic Brownies cut into squares.

Tips for the perfect ganache

  • Like noted above, 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.

Now you’re squared away with all the tips and tricks you need to make these cute cosmic brownies! If you have kids, I know they’d be tickled to find this delicious treat in their lunchbox.

More Back to school recipes:

  • No-Bake Energy Bites – the perfect healthy snack for their lunchbox, or YOUR lunch box 🙂
  • Baked Oatmeal Cups – portable breakfast option, with lots of tips and tricks for making the recipe even healthier.
  • Beet Hummus – would be great in a lunch box! Dip carrots, pretzels, naan, or cucumbers in it.

A bite taken out of a cosmic brownie.

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Cosmic brownies on a white parchment paper.
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5 from 1 vote

Cosmic Brownies

These homemade cosmic brownies are ultra rich and fudgy! Dare i say, WAY BETTER than the store bought version.
prep time 15 mins
cook time 25 mins
total time 40 mins
servings: 24 brownies

INGREDIENTS

  • 1 cup granulated sugar
  • 3/4 cup light brown sugar packed
  • 12 tablespoons unsalted butter melted
  • 2 large eggs
  • 1 egg yolk
  • 1 teaspoon vanilla extract
  • 1 cup all purpose flour
  • 3/4 cup unsweetened natural cocoa powder
  • 2 teaspoon cornstarch
  • pinch salt
  • rainbow chips

Ganache

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

INSTRUCTIONS

Brownies

  • 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. 

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. 

RECIPE NOTES

Ganache Making Tips: Make sure you wait 3-5 minutes after pouring the hot cream over the chocolate. The waiting period lets the cream melt the chocolate while bringing down the temp of the cream. If you whisk the cream and chocolate while the cream is still really hot it can cause the ganache to break which will result in a gritty texture.
Course: Dessert
Cuisine: American
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