Thick, fudgy, loaded with a silky chocolate ganache, and finished with a shower of rainbow candy sprinkles these Cosmic Brownies are the kind of treat that makes people stop mid-bite and ask for the recipe. I first made these on a rainy Saturday afternoon when my pantry was full but my motivation was low, and honestly? They came together so easily I almost felt guilty calling myself a baker. If you've got one bowl and about 40 minutes, you're already halfway there.
The Cosmic Brownies base is dense and rich, almost like a truffle in bar form. The ganache on top sets into this glossy, slightly firm chocolate layer that just cracks when you bite into it. And those rainbow sprinkles add a little crunch and a lot of personality. If you love Best Ice Cream Cake Recipe or anything in the world of dessert recipes, these are going to be your new obsession. They're also a wonderful companion to Healthy Strawberry Muffins Recipe when you're putting together a little dessert spread.
Why You'll Love This Cosmic Brownies
These are genuinely hard to mess up. The batter comes together in one bowl, the ganache takes maybe five minutes to make, and the whole thing chills while you go do literally anything else. They slice cleanly when cold, hold their shape, and look like you ordered them from a bakery. Kids love them because of the sprinkles. Adults love them because of the ganache. Everyone goes back for a second square.
They also keep beautifully in the fridge, which means you can make them a day ahead for a party or just have them waiting for you all week. That's a win.
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Cosmic Brownies Ingredients
Here's everything you'll need, and why each piece matters.
See Recipe Card Below This Post For Ingredient Quantities
For the Fudge Brownies:
- Unsalted butter : Melted butter gives these brownies that dense, fudgy texture instead of a cakey crumb. Using unsalted butter lets you control the salt yourself.
- Granulated sugar : Adds sweetness and helps create a slightly crackly top as the brownies bake.
- Light brown sugar : Brings a soft molasses warmth that deepens the chocolate flavor and adds moisture.
- Eggs : Bind everything together and add structure. Room temperature eggs blend in more smoothly.
- Neutral oil : Just a tablespoon adds extra moisture and keeps the brownies soft even after chilling.
- Pure vanilla extract : Rounds out the chocolate flavor and adds depth.
- All-purpose flour : Provides just enough structure to hold these together without making them cakey. Measure carefully.
- Cocoa powder : The backbone of the chocolate flavor. Use a good quality unsweetened cocoa for the best results.
- Baking soda : A tiny touch of lift. Optional, but it helps the brownies set up with a slightly smoother top.
- Kosher salt : Balances the sweetness and makes the chocolate taste more like itself.
For the Frosting:
- Heavy whipping cream : The base of the ganache. It melts the chocolate into a smooth, pourable frosting.
- Semisweet chocolate, chopped : Adds rich, slightly bitter chocolate notes to balance the sweetness of the milk chocolate.
- Milk chocolate, chopped : Softens the ganache and gives it that familiar, creamy sweetness.
- Salted butter : Stirred in at the end for shine and a silky smooth finish.
- Rainbow chocolate chip sprinkles : The signature topping. They add color, a little crunch, and all the fun.
How To Make Cosmic Brownies
Preheat the oven: Preheat your oven to 350°F (175°C). Grease an 8x8-inch nonstick baking pan and line it with parchment paper, leaving at least 2 inches of overhang on the sides. That overhang is your best friend when it's time to lift the brownies out.
Mix the sugars and butter: In a medium-sized bowl, combine the melted butter, granulated sugar, and brown sugar. Use a hand mixer on medium speed and blend until well incorporated and slightly smooth.
Add the eggs: Add the eggs one at a time, mixing after each addition until fully blended. Don't rush this part. Each egg needs to be fully mixed in before the next one goes in.
Stir in oil and vanilla: Add the tablespoon of oil and the vanilla extract. Stir until smooth. The batter should look glossy at this point.
Whisk the dry ingredients: In a separate bowl, whisk together the flour, cocoa powder, baking soda (if using), and salt. Make sure there are no lumps in the cocoa before adding it to the wet ingredients.
Combine wet and dry: Reduce the mixer speed and gradually add the dry ingredients to the wet ingredients in intervals, mixing until just fully incorporated. Don't overmix. The batter will be thick and fudgy.
Bake: Pour the batter into your prepared pan and spread it evenly with a spatula. Bake for 30 minutes, or until a toothpick inserted into the center comes out just barely clean. A few moist crumbs clinging to the toothpick is perfect.
Cool completely: Let the brownies cool in the pan for a full hour, or until they reach room temperature. Don't rush this. Warm brownies and warm ganache are a melty mess.
Make the ganache: Place the heavy cream in a microwave-safe bowl and heat it in 15-second increments until very hot but not boiling, stirring between each round. Add the chopped semisweet and milk chocolates to the hot cream. Let it sit for 1 minute, then whisk until completely smooth and glossy.
Finish the ganache: Stir in the salted butter until fully melted and the ganache looks silky and smooth.
Frost the brownies: Pour the ganache over the cooled brownies. Use a flat spatula to spread it evenly all the way to the edges.
Add the sprinkles: Let the ganache cool for about 5 minutes, then scatter the rainbow chocolate chip sprinkles over the top while the frosting is still slightly tacky so they stick.
Chill and set: Cover the pan and refrigerate for about 1 hour, or until the frosting is fully set and firm to the touch.
Slice and serve: Use the parchment paper to lift the whole slab out of the pan. Transfer to a cutting board and cut into squares. A sharp knife wiped clean between cuts gives you the cleanest slices.
Substitutions
No milk chocolate on hand? You can use all semisweet chocolate in the ganache. It'll be slightly less sweet and a little more intense, which some people actually prefer.
Dairy-free? Swap the butter for a good quality vegan butter and use full-fat coconut cream in place of the heavy cream. The ganache texture will be slightly softer but still delicious.
Want to skip the oil in the brownie batter? You can, but the brownies will be slightly less moist after they chill. The oil is a small addition that makes a noticeable difference.
Equipment For Cosmic Brownies
- 8x8-inch nonstick baking pan
- Parchment paper
- Medium mixing bowls
- Hand mixer
- Whisk
- Flat spatula
- Microwave-safe bowl
- Sharp knife for slicing
Storage Your Cosmic Brownies
Refrigerator: Store the Cosmic Brownies in an airtight container or wrapped tightly in plastic wrap in the fridge for up to 5 days. Let them sit at room temperature for about 10 minutes before serving so the ganache softens slightly.
Freezer: Wrap individual brownies tightly and store in a freezer-safe bag or container for up to 3 months. Thaw at room temperature before eating.
Room temperature: The ganache can get soft and sticky at room temperature, especially in a warm kitchen. For best results, keep them refrigerated until just before serving.
Serving Suggestions
These Cosmic Brownies are rich on their own, but if you want to take them further, here are a few simple ideas.
A cold glass of milk is the classic pairing, and honestly it's classic for a reason. The cold milk against the dense, chocolatey brownie is hard to beat.
Warm a brownie for 10 to 15 seconds in the microwave and add a scoop of vanilla ice cream on top. The ganache gets slightly melty and the whole thing is incredible.
Cut them into smaller pieces and add them to a dessert board alongside fresh berries and other bite-sized sweets. They look beautiful next to Best Pumpkin Muffins Recipe on a fall dessert spread.
They're also a great make-ahead treat for kids' birthday parties, bake sales, or any time you need something that looks impressive without a lot of effort.
Expert Tips
Use good quality chocolate for the ganache. It doesn't have to be fancy, but the chocolate you chop yourself will melt more smoothly than chocolate chips, which have stabilizers in them.
Chop the chocolate finely and evenly before adding it to the cream. Smaller pieces melt faster and more evenly.
Don't skip the chilling time. The ganache needs that hour in the fridge to fully set so you get clean slices and that satisfying snap when you bite in.
Line the pan generously with parchment. Those overhanging edges are the only thing standing between you and a broken brownie slab.
Let the ganache cool for a few minutes before adding the sprinkles. If it's too hot, the candy coating on the sprinkles can bleed color into the frosting.
FAQ
Can you get cosmic brownies in the UK?
Little Debbie Cosmic Brownies are an American brand and aren't widely sold in UK stores. But the good news is that homemade Cosmic Brownies are even better than the packaged version, and all the ingredients are easy to find at any UK supermarket. You might just need to look for rainbow hundreds and thousands in place of the rainbow chip sprinkles.
What is a Cosmic Brownies made of?
A Cosmic Brownies is made with a dense fudge brownie base, a chocolate ganache or fudge frosting on top, and rainbow-coated candy sprinkles scattered over the frosting. The combination of chewy brownie, silky chocolate topping, and crunchy colorful sprinkles is what makes them so recognizable and so fun to eat.
Why are cosmic brownies so high in calories?
Cosmic Brownies are calorie-dense because they're made with butter, two kinds of sugar, eggs, cocoa powder, and a ganache frosting made from heavy cream and two types of chocolate. Every ingredient contributes fat or sugar, and the servings are generous. At 523 calories per brownie, they're a real indulgent treat, which is exactly the point. Cut them smaller if you want a lighter portion.
How many calories in a Cosmic Brownies?
Each homemade Cosmic Brownie in this recipe contains 523 calories per serving, based on the recipe cut into 9 equal squares. That includes the fudge brownie base, the full chocolate ganache frosting, and the rainbow sprinkles on top.
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Pairing
These are my favorite dishes to serve with Cosmic Brownies
Cosmic Brownies
Ingredients
For the Fudge Brownies:
- ½ cup unsalted butter melted
- ¾ cup granulated sugar
- ½ cup packed light brown sugar
- 2 large eggs room temperature
- 1 tablespoon neutral oil such as vegetable oil
- 2 teaspoon pure vanilla extract
- ¾ cup all-purpose flour
- ½ cup cocoa powder unsweetened
- ¼ teaspoon baking soda optional
- ½ teaspoon kosher salt
For the Frosting:
- ½ cup heavy whipping cream
- 4 oz semisweet chocolate chopped
- 4 oz milk chocolate chopped
- 1 tablespoon salted butter
- ½ cup rainbow chocolate chip sprinkles
Instructions
- Preheat the oven to 350°F (175°C). Grease an 8×8-inch nonstick baking pan and line it with parchment paper, leaving at least 2 inches hanging over the edges.
- In a medium-sized bowl, beat the melted butter, granulated sugar, and brown sugar with a hand mixer on medium speed.
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Add eggs one at a time, mixing well after each addition.
- Stir in the oil and vanilla extract.
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In a separate bowl, whisk together the flour, cocoa powder, baking soda (if using), and salt. Slowly add the dry ingredients to the wet mixture while mixing at a low speed until fully incorporated.
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Pour the brownie batter into the prepared pan and spread evenly. Bake for 30 minutes or until a toothpick inserted into the center comes out just barely clean.
- Allow the brownies to cool in the pan for about an hour or until they are close to room temperature.
- Place the heavy cream in a microwave-safe bowl. Heat in 15-second increments until hot, stirring in between.
- Add the chopped semisweet and milk chocolates to the hot cream and let sit for a minute. Whisk until smooth.
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Stir in the salted butter until completely melted and incorporated.
- Pour the ganache over the cooled brownies. Use a spatula to spread it evenly. Let sit for 5 minutes to set.
- Sprinkle the rainbow chocolate chip sprinkles evenly over the ganache.
- Cover the brownies and refrigerate for about 1 hour or until the frosting is set. Use the parchment paper to lift the brownies out of the pan and cut into squares.
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