There are some childhood treats that you never really forget, and Cosmic Brownies are definitely one of them. That rich chocolate brownie, sweet chocolate topping, and little bit of crunch made them feel like such a special treat.
This homemade version brings back all those nostalgic flavors but gives them a delicious homemade upgrade. Instead of a simple chocolate coating, these brownies are finished with a warm, velvety chocolate ganache that settles slightly into the brownie as it cools. The result is a soft, fudgy chocolate layer topped with a smooth, decadent frosting and a little salty crunch from roasted sunflower seeds.
They are easy enough to make for a weekend dessert but special enough for birthday parties, summer barbecues, bake sales, or whenever you are craving an old-fashioned chocolate treat.
What Are Cosmic Brownies?
Cosmic Brownies are a classic packaged chocolate snack known for their rich brownie base, chocolate frosting, and colorful candy toppings. They have been a favorite childhood treat for generations.
This homemade version keeps the fun, nostalgic idea but takes the chocolate flavor up a notch. The brownie is soft and tender, while the warm chocolate ganache creates a smooth topping that sets beautifully in the refrigerator.
Instead of traditional candy toppings, this recipe uses salted roasted sunflower seeds for a sweet-and-salty combination. Of course, you can easily switch those out for chocolate chips, candy-coated chocolates, sprinkles, or your favorite brownie topping.
Why We Love This Homemade Version
What makes these homemade Cosmic Brownies especially fun is that you get to take a familiar childhood treat and make it your own.
The warm chocolate ganache is probably my favorite part. It is smooth and glossy when poured over the brownies, then firms up into a rich chocolate topping as it chills. It also has a slightly softer texture than a traditional chocolate frosting, which makes every bite feel extra decadent.
I also love the addition of salted roasted sunflower seeds. The little bit of saltiness balances the sweetness of the brownies and frosting, while the seeds add a pleasant crunch.
And because this recipe makes a large 13×9-inch pan, there is plenty to share. They are perfect for bringing to a family gathering, summer barbecue, birthday party, or potluck.
Fudgy Cosmic Brownies Topped with Perfect Ganache
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Kitchen Essentials
Ingredients
Cake
- ¾ Cup Butter (1 ½ sticks) room temp
- 1 ½ Cup Sugar
- 2 Large Eggs
- 1 Teaspoon Vanilla
- 1 ⅔ Cups Flour
- ⅔ Cups Unsweetened Cocoa Powder
- ¾ Teaspoon Baking Soda
- ¾ Teaspoon Salt
- 1 Cup Hot Water (very hot, does not need to be boiling)
Frosting
- ⅔ Cup Heavy Cream
- 2 Tablespoons Sugar
- 6 Ounces Semi-Sweet Chocolate Chips roughly chopped
- 2 Tablespoons Butter softened
- 1/2 Cup Salted Roasted Sunflower Seeds or topping of your choice such as chocolate chips or chocolate candies
Instructions
Make the Brownies
- Preheat the oven to 350°F. Generously grease a 13×9-inch rimmed baking sheet with butter, then lightly dust with flour. Tap out any excess flour.
- Add the softened butter and sugar to the bowl of a stand mixer. Beat on medium-high speed for about 3 minutes, until light and fluffy.¾ Cup Butter, 1 ½ Cup Sugar
- Add the eggs one at a time, mixing well after each addition. Stir in the vanilla.2 Large Eggs, 1 Teaspoon Vanilla
- In a separate bowl, whisk together the flour, cocoa powder, baking soda, and salt. Do this to remove any lumps.1 ⅔ Cups Flour, ⅔ Cups Unsweetened Cocoa Powder, ¾ Teaspoon Baking Soda, ¾ Teaspoon Salt
- Pour the water into a microwave-safe cup and heat for about 2 minutes, or until very hot and steaming. It does not need to boil.1 Cup Hot Water
- With the mixer on low, add the dry ingredients and hot water to the butter mixture in alternating additions, beginning and ending with the dry ingredients. Mix just until the flour is incorporated. The batter will be light and mousse-like.
- Pour the batter into the prepared pan. Use an offset spatula to spread it evenly into the corners.
- Bake for 20–25 minutes, or until a toothpick inserted into the center comes out clean.
- Place the pan on a wire rack and allow the brownies to cool completely in the pan.
Make the Ganache
- Add the heavy cream and sugar to a saucepan. Heat over medium heat, stirring occasionally, until the mixture reaches a gentle boil. Remove from the heat as soon as it begins bubbling.⅔ Cup Heavy Cream, 2 Tablespoons Sugar
- Add the chopped chocolate and let it sit undisturbed for about 3 minutes. Whisk until completely smooth.6 Ounces Semi-Sweet Chocolate Chips
- Stir in the softened butter until melted and the ganache is glossy.2 Tablespoons Butter
- Pour the warm ganache evenly over the completely cooled brownies. Immediately sprinkle the sunflower seeds or your desired topping over the chocolate.1/2 Cup Salted Roasted Sunflower Seeds
- Allow the brownies to sit at room temperature for about 30 minutes, then cover and refrigerate until completely set, preferably overnight.
- Cut into squares and serve.
Your Own Private Notes
Notes
Recipe Tips from our Kitchen
Hot water: The water should be very hot and steaming. It helps bloom the cocoa powder and brings out a deeper chocolate flavor. For clean cuts: Refrigerate the brownies until completely set. Use a sharp knife and wipe it clean between cuts. Topping ideas: Swap the sunflower seeds for mini chocolate chips, colorful candy-coated chocolates, sprinkles, chopped nuts, or other favorite toppings. Storage: Store covered in the refrigerator for several days. Let the brownies sit at room temperature for a few minutes before serving for a softer texture. Freezing: Cut the chilled brownies into individual squares and freeze in an airtight container, separating layers with parchment paper. Thaw in the refrigerator before serving.Nutrition
Recipe Variations
One of the best things about homemade Cosmic Brownies is how easy they are to change.
Classic Candy Topping: Use colorful candy-coated chocolate pieces for a fun topping that is closer to the nostalgic look of the original treat.
Chocolate Chip Brownies: Sprinkle mini chocolate chips over the warm ganache before it sets.
Rainbow Sprinkles: Add colorful sprinkles for birthday parties, celebrations, or a kid-friendly dessert.
Chocolate Sprinkles: Keep things simple with chocolate sprinkles for even more chocolate flavor.
Peanut Butter: Add a handful of peanut butter chips to the brownie batter or sprinkle them over the warm ganache.
Dark Chocolate: Use dark chocolate chips instead of semi-sweet chocolate for a deeper chocolate flavor.
Milk Chocolate: For a sweeter topping, substitute milk chocolate for the semi-sweet chocolate.
Nutty Topping: Chopped peanuts, pecans, or walnuts can add a delicious crunch. If you are serving these to a crowd, be sure to let everyone know about the nuts.
Holiday Brownies: Change the sprinkles or candy colors to match Christmas, Valentine’s Day, Halloween, birthdays, or other celebrations.
How to Get Clean Brownie Cuts
For those beautiful bakery-style squares, patience is your best friend.
Once the ganache has been added, allow the brownies to cool at room temperature for about 30 minutes. Then cover and refrigerate until completely chilled and set.
When you are ready to cut them, use a sharp knife. For especially clean cuts, run the knife under hot water, dry it thoroughly, and then slice. Wipe the knife clean between cuts and repeat as needed.
You can also cut the brownies into smaller squares if you are serving them at a party. They are rich enough that a little square can go a long way.
How to Store Cosmic Brownies
Because of the chocolate ganache topping, these brownies are best stored in the refrigerator.
Cover the pan tightly with plastic wrap or transfer the brownies to an airtight container. They will keep well in the refrigerator for several days.
Let them sit at room temperature for a few minutes before serving if you prefer a softer brownie and slightly creamier chocolate topping.
During cooler weather, they can also be kept at room temperature for short periods, but refrigeration is the better choice for longer storage and especially during warm summer months.
Why Are These Brownies So Popular?
There is something about a chocolate brownie topped with even more chocolate that is hard to resist. These brownies have several things going for them.
They are wonderfully chocolatey. The cocoa powder in the brownie and the semi-sweet chocolate ganache give you plenty of rich chocolate flavor without relying on a boxed brownie mix.
They have a nostalgic flavor. If you grew up eating Cosmic Brownies, that first bite brings back memories of a favorite childhood snack.
The texture is just right. The brownie layer is soft and tender, while the ganache adds a smooth, creamy topping.
They are easy to make. There is no complicated decorating or special equipment needed. Once the brownie is baked and cooled, the ganache comes together quickly.
They are easy to customize. You can use different toppings depending on what you have in your pantry or what you are serving them for.
And perhaps the best part? They are the kind of dessert that tends to disappear quickly once they are cut and placed on a serving platter.
Can You Freeze Cosmic Brownies?
Yes, these brownies can be frozen.
For best results, cut the completely chilled brownies into individual squares first. Place them in an airtight freezer-safe container, separating layers with parchment paper so the chocolate topping does not stick.
Freeze for up to about 2 to 3 months for the best quality.
Thaw the brownies in the refrigerator overnight or allow individual pieces to thaw at room temperature before serving.
Creative Ways to Use Leftover Cosmic Brownies
If you happen to have leftovers, there are plenty of fun ways to enjoy them besides simply eating another square.
Brownie Sundaes: Warm a brownie slightly and top it with vanilla ice cream, chocolate sauce, and a few extra toppings.
Brownie Parfaits: Cut the brownies into small pieces and layer them with whipped cream and chocolate pudding or vanilla ice cream.
Ice Cream Topping: Crumble a brownie over a bowl of ice cream for an easy chocolate topping.
Milkshake: Blend a brownie with vanilla or chocolate ice cream and milk for an extra-decadent milkshake.
Dessert Trifle: Layer brownie pieces with pudding, whipped cream, and berries in a large glass bowl for a fun party dessert.
Brownie Crumbles: Break leftover brownies into small pieces and use them as a topping for yogurt, ice cream, or pudding.
Can I make these Cosmic Brownies ahead of time?
Absolutely. In fact, these brownies are an excellent make-ahead dessert. The brownie and ganache have time to cool and set, and the flavor and texture are wonderful after chilling overnight.
Do Cosmic Brownies need to be refrigerated?
For this homemade version, refrigeration is recommended because of the chocolate ganache topping. They can be brought to room temperature before serving.
Can I use a different size pan?
A 13×9-inch rimmed baking sheet is recommended because it gives you the right thickness for the brownie layer. Using a significantly smaller pan will result in thicker brownies and may require additional baking time.
Why did my ganache turn out too thin?
The ganache should be warm and pourable when you spread it over the brownies, but it will firm as it cools. Make sure the brownie layer is completely cool before adding it and allow enough time for the finished brownies to chill.
Can I use milk chocolate instead of semi-sweet chocolate?
Yes. Milk chocolate will make the topping sweeter and a little milder in chocolate flavor.
What can I use instead of sunflower seeds?
You can use mini chocolate chips, colorful candy-coated chocolates, sprinkles, chopped nuts, or another favorite brownie topping.
Can I make these brownies without a stand mixer?
Yes. A hand mixer works well, or you can cream the butter and sugar together with a sturdy wooden spoon. The important thing is to beat the butter and sugar until they are light and fluffy.
Why do you add hot water to the brownie batter?
The hot water helps bloom the cocoa powder, which intensifies the chocolate flavor. It also contributes to the soft, tender texture of the brownie.
A Few More Tips for Success
- Measure the flour and cocoa powder accurately. Too much flour can make the brownies dry.
- Make sure the butter is softened but not melted.
- Scrape down the sides of the mixing bowl as needed so everything incorporates evenly.
- Don’t skip greasing and flouring the baking pan.
- Watch the brownies closely toward the end of the baking time. You want the center set without overbaking.
- Cool the brownies completely before adding the ganache.
- Add your toppings while the ganache is still warm so they stick.
- For the neatest slices, refrigerate the brownies overnight.
The Perfect Homemade Chocolate Treat
These Cosmic Brownies are a fun reminder that sometimes the best recipes are the ones that bring back a little nostalgia. You get all the chocolatey goodness you remember from childhood, but with a homemade brownie and rich ganache that make this version feel extra special.
Whether you make them for a birthday party, summer barbecue, family gathering, or simply because you are craving something chocolatey, these brownies are sure to be a hit. And don’t be surprised if the pan disappears faster than you expected!
Make a batch, let them chill, cut them into squares, and enjoy a homemade version of a childhood favorite.
My family loved this!