These homemade cosmic brownies bring a fudgy chocolate base, a silky ganache topping, and a colorful scatter of rainbow candy pieces.
They are the lunchbox treat many people remember from childhood, made with real butter, cocoa, and chocolate. The batter takes a single bowl, and the ganache needs only two ingredients.
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Why This Homemade Cosmic Brownies Recipe Works
Melted butter and cocoa give a dense, fudgy crumb without any mixer. Brown sugar adds moisture, so the brownies stay soft even after chilling.
The ganache uses just cream and chocolate chips, which set to a soft, fudge like layer that holds the candy pieces in place.
Baking at 325 degrees F keeps the edges tender, so the squares slice cleanly once the topping sets.
Ingredients for Homemade Cosmic Brownies
- 3/4 cup all purpose flour
- 2/3 cup unsweetened cocoa powder
- 12 tablespoons unsalted butter, melted (1 1/2 sticks)
- 1 cup granulated sugar
- 1/2 cup brown sugar, packed
- 2 large eggs, room temperature
- 1 teaspoon pure vanilla extract
- 3/4 teaspoon kosher salt
- 1 cup semisweet chocolate chips, for the ganache
- 1/2 cup heavy cream
- 1/4 cup rainbow candy coated chocolate pieces, for topping
Unsweetened cocoa powder. It provides the deep chocolate flavor. Sift it if it looks lumpy.
Melted unsalted butter. Melted butter gives a chewy, fudgy texture and mixes by hand.
Heavy cream. Cream gives the ganache body and shine. Heat it until steaming but not boiling.
Semisweet chocolate chips. They melt into a smooth topping that sets soft but sliceable.
Rainbow candy pieces. Choose small candy coated chocolate pieces and press them lightly into the ganache.
How to Make Homemade Cosmic Brownies
1. Prepare the pan Heat the oven to 325 degrees F. Spray a 9×9 inch pan and line it with parchment paper, leaving an overhang.
2. Whisk the dry ingredients Whisk the flour and cocoa together in a medium bowl and set aside.
3. Mix the wet ingredients In a larger bowl, whisk the melted butter with both sugars until smooth. Add the eggs, vanilla, and salt and mix well.
4. Combine and bake Stir in the flour mixture until just combined. Spread the batter in the pan and bake for 30 to 35 minutes, until a toothpick comes out nearly clean.
5. Make the ganache Cool the brownies completely. Heat the cream in a small pot until steaming, then pour it over the chips and stir until smooth.
6. Top and set Spread the ganache over the brownies, scatter the rainbow pieces on top, and chill until set before cutting into 16 squares.
How to Serve Homemade Cosmic Brownies
Cut the chilled brownies into 16 squares with a sharp knife wiped clean between cuts. Serve them with cold milk or beside fudgy chocolate chunk brownies for a brownie sampler. A spoonful of dark chocolate mousse and a swirl of creamy chocolate buttercream make a fun dessert board, while a cup of berry kefir smoothie adds a fruity contrast.
How to Store and Reheat Homemade Cosmic Brownies
Store the brownies in an airtight container in the refrigerator for up to 4 days, since the ganache needs to stay cool. Let squares sit at room temperature for 10 minutes before serving. To freeze, wrap the cut squares well and keep them for up to 3 months, then thaw overnight in the refrigerator.
Tips and Variations for Homemade Cosmic Brownies
Cool completely. Warm brownies melt the ganache and make the topping slide.
Do not overmix. Stir the flour in until no streaks remain, then stop.
Use a clean knife. Wipe the blade between cuts for sharp edges.
Press gently. Press candy pieces into the ganache while it is still soft so they stay put.
Swap the chocolate. Milk or dark chips change the sweetness of the topping.
Add salt. A tiny pinch of flaky salt on top balances the sweetness.
Skip the raw batter. The batter contains raw eggs and raw flour, so only taste the finished brownies.
Chill safely. Refrigerate leftovers within two hours, using the Texas AgriLife Extension food safety guide as a reference.
Frequently Asked Questions About Homemade Cosmic Brownies
What are homemade cosmic brownies?
They are fudgy brownies topped with chocolate ganache and colorful candy coated chocolate pieces.
How do you make homemade cosmic brownies without a mixer?
Whisk melted butter with the sugars by hand, then stir in the remaining ingredients with a spatula.
How long do homemade cosmic brownies keep?
Keep them in the refrigerator for up to 4 days or freeze them for 3 months.
Can I use salted butter?
Yes, but omit the kosher salt so the brownies are not too salty.
How do I get a smooth ganache?
Heat the cream until steaming, pour it over the chips, wait two minutes, then stir slowly until glossy.
Homemade Cosmic Brownies with Chocolate Ganache
Equipment
- 9×9 inch baking pan
- Parchment paper
- 2 mixing bowls
- Small saucepan
- Whisk
Ingredients
Main Ingredients
- ¾ cup all purpose flour
- ⅔ cup unsweetened cocoa powder
- 12 tbsp unsalted butter melted, 1 1/2 sticks
- 1 cup granulated sugar
- ½ cup brown sugar packed
- 2 large eggs room temperature
- 1 tsp pure vanilla extract
- ¾ tsp kosher salt
- 1 cup semisweet chocolate chips for the ganache
- ½ cup heavy cream
- ¼ cup rainbow candy coated chocolate pieces for topping
Instructions
Cooking
- Prep the pan. Heat the oven to 325 degrees F, spray a 9×9 inch pan, and line it with parchment.
- Mix the dry ingredients. Whisk the flour and cocoa together in a bowl.
- Make the batter. Whisk the melted butter and both sugars, then mix in the eggs, vanilla, and salt. Fold in the dry ingredients until just combined.
- Bake. Spread the batter in the pan and bake 30 to 35 minutes, until a toothpick comes out nearly clean. Cool for 1 hour.
- Make the ganache. Heat the cream until steaming, pour it over the chips, rest 2 minutes, and stir smooth. Spread it over the cooled brownies.
- Top and chill. Scatter the rainbow pieces over the ganache and chill for 30 minutes before cutting.
