Homemade Cosmic Brownies
These homemade Cosmic Brownies feature ultra fudgy brownies topped with a simple chocolate ganache frosting and candy-coated chocolate chips. Just like your favorite store-bought brownies, but better!
As a kid, there was no better feeling than opening up your lunchbox to discover that Mom had snuck a Cosmic Brownie in as a treat. The dense, fudgy brownie topped with chocolate frosting and rainbow chocolate chips hit the spot every time!
Although I have fond memories of digging into those store-bought brownies, I’d much rather enjoy homemade sweet treats these days.
Enter: these homemade Cosmic Brownies. They’re even richer and fudgier than my classic brownies, and they’re topped with an easy three-ingredient chocolate ganache frosting.
Although this Cosmic Brownie recipe has a few extra steps to it, the process is as straightforward as making regular brownies. You will have to be patient though, as the frosting needs to chill in the fridge for an hour or two to set up!
Recipe Ingredients
This Cosmic brownie recipe has three components: a dense brownie base, a fudge frosting for the brownies, and the rainbow candy-coated chocolate chips. Let’s go over a few important ingredients you’ll need to make this childhood favorite at home.
- Butter: I prefer using unsalted butter when baking since the amount of salt in salted butters varies between brands. If you only have salted butter on hand, just omit the salt or reduce it to a tiny pinch.
- Granulated Sugar & Brown Sugar: In my classic brownie recipe, I only use granulated sugar. But for this recipe, you will be using a mix of granulated and brown sugar. Just 1/2 cup of brown sugar adds moisture and flavor to the brownies, giving them that classic Cosmic Brownie texture and taste.
- Eggs: You’ll need three whole eggs and one egg yolk to make this recipe. The extra egg yolk adds more fat so that the brownies are super dense and fudgy. Make sure your eggs are at room temperature before whisking them into the batter.
- Cocoa Powder: The brownies are made solely with cocoa powder and no melted chocolate. You can use either unsweetened natural cocoa powder or Dutch-process cocoa powder.
- Semi-sweet Chocolate: I recommend chopping two 4-ounce bars of chocolate and melting them to make the fudge frosting rather than use chocolate chips, which contain stabilizers and are more resistant to melting.
- Corn Syrup: This ingredient is optional, but it makes the chocolate brownie frosting glossy. If you don’t have any on hand, you may omit it.
- Cosmic Brownie Sprinkles: I used rainbow candy-coated chocolate chips on top of the ganache frosting. You can find them at Walmart, on Amazon, or you can substitute them with mini M&M’s or regular sprinkles.
How to Make Cosmic Brownies
Making copycat Cosmic Brownies at home couldn’t be simpler! First, you’ll need to make the fudgy brownies.
- Whisk together the wet ingredients: In a large bowl, whisk together the melted butter and sugars. Then, whisk in the eggs, egg yolk, and vanilla.
- Add the dry ingredients: The dry ingredients can be added directly to the wet mixture. I recommend sifting them into the mixing bowl to ensure there are no lumps in the batter.
- Bake the brownies: Pour the batter into a parchment paper or foil-lined 9×13-inch baking dish. Bake until a toothpick inserted in the center comes out clean, but with a few moist crumbs.
After the brownies come out of the oven, you must let them cool completely before topping them with the chocolate ganache frosting.
- Add the chopped chocolate and corn syrup to a bowl: Set this aside while you heat the heavy cream.
- Heat the heavy cream: You can do this on the stove over medium-low heat, or you can heat the cream in the microwave.
- Pour the cream over the chopped chocolate: Pour the simmering cream over the chopped chocolate and corn syrup and let rest for 3 minutes before whisking it all together. If all of the chocolate has not melted, microwave the mixture in 20-second increments until it’s smooth.
- Frost the brownies: Smooth the ganache frosting over the cooled brownies, then sprinkle with candy-coated chocolate chips.
- Chill the brownies: The frosting needs time to firm up in the fridge, about 1 to 2 hours. If you try to cut the brownies right away, the frosting will ooze all over the pan and you won’t have perfect homemade Cosmic Brownies.
Storage Instructions
The ganache will soften at room temperature, so it’s best to keep these brownies refrigerated. Cover the pan with plastic wrap, or transfer the brownies to an airtight container. They’ll last up to five days in the fridge.
Can This Recipe Be Made in Advance?
Yes, you can bake the brownies a day in advance and frost them the day you plan on serving them. Or, prepare the entire Cosmic Brownie recipe as written up to 24 hours before slicing and serving. The brownies keep well in the fridge, tightly covered.
Can Mix-Ins Be Added to the Batter?
Absolutely! Store-bought Cosmic Brownies don’t contain any mix-ins so I didn’t use any in this recipe. However, mini chocolate chips or finely chopped nuts would be delicious in these brownies. I suggest only using about 1 cup of mix-ins if you do add them.
Baking Tips
- I recommend lining your pan with foil or parchment paper and leaving some overhang. This will make it much easier to remove the brownies from the pan!
- Room temperature eggs will mix much easier into the batter. If you forget to set them out ahead of time, place them in a bowl of warm water for 5 to 10 minutes.
- The corn syrup in the chocolate brownie frosting is optional, but recommended. It makes the frosting glossy and gives the brownies a store-bought appearance.
- You MUST let the brownies cool completely before frosting them. If needed, you can make the brownie base in advance, then frost them later on when you have time.
- Want to freeze these brownies? Slice the chilled brownies, wrap each one tightly with plastic wrap, and store them in a large freezer bag/container for up to 3 months. When you’re ready to enjoy them, thaw overnight in the refrigerator.
More Easy Brownie Recipes to Make!
Recipe Video
If you want to see a full video tutorial on how these brownies are made, you can watch the video below!
Homemade Cosmic Brownies
Ingredients
For the Brownies:
- 1 cup unsalted butter melted and slightly cooled (2 sticks, 230 grams)
- 1 ¾ cups granulated sugar (350 grams)
- ½ cup packed light brown sugar (100 grams)
- 3 large eggs at room temperature
- 1 large egg yolk at room temperature
- 1 teaspoon pure vanilla extract
- 1 cup unsweetened cocoa powder (90 grams)
- 1 cup all-purpose flour spooned & leveled (125 grams)
- ½ teaspoon salt
For the Ganache:
- 8 ounces semisweet chocolate finely chopped (226 grams)
- 1 tablespoon light corn syrup optional but adds glossiness (20 grams)
- ½ cup heavy cream (120 ml)
For the topping:
- Rainbow candy coated chocolate chips, mini m&m's, or sprinkles
Instructions
- To make the brownies: Preheat the oven to 350°F (180°C). Line a 9x13-inch baking pan with foil or parchment paper, making sure to leave some overhang for easy removal. If using foil, spray it well with nonstick cooking spray, and set aside.
- In a large mixing bowl, whisk together the melted butter, granulated sugar, and brown sugar until well combined. Then whisk in the eggs, egg yolk, and vanilla extract until fully combined.
- Sift in the cocoa powder, flour, and salt and continue whisking until just combined, stopping to scrape down the sides of the bowl as needed.
- Scoop the batter into the prepared baking pan and spread it around into one even layer. Bake for 27 to 33 minutes or until a toothpick inserted into the center comes out clean with just a few moist crumbs.
- Remove from the oven and allow to cool completely.
- To make the ganache: Place the chopped chocolate and corn syrup into a large heatproof bowl. Set aside.
- Heat the heavy cream in a medium pot and bring to a simmer on the stove (or heat in the microwave for 45 seconds to 1 minute).
- Pour the simmering cream over the chocolate and let it sit for 3 minutes.
- Mix with a rubber spatula or spoon until the mixture is smooth and well combined. If any chocolate clumps remain, microwave in 20 to 30-second increments until melted and smooth.
- Use a spatula or spoon to spread the chocolate ganache over the cooled brownies.
- Sprinkle with rainbow candy coated chocolate chips, mini M&Ms, or sprinkles. Refrigerate for 1 to 2 hours to allow the ganache to set before serving. Cut into squares when ready to serve!
They discontinued the little Debbie’s line in Canada so my partner and I have been craving it for so long. This recipe is even better! They are sooo delicious and fudgey. The texted is amazing it was perfect!
The recipe was easy to follow and complete. Overall, it tastes good! However, it much more fudge-like than I would have wanted. I know cosmic brownies are a bit fudgy, but I would would say they still have some brownie/cake-like consistency. This recipe is mostly fudge with frosting on top. Again, these brownies do taste good but are not comparable to a cosmic brownie in my opinion.
I have made this recipe at LEAST 6 times in the past eight weeks. In fact, I made it for the first time the night before my daughter was born. It was the perfect distraction from the contractions 🙂
My family and friends love it and have requested it multiple times. This recipe couldn’t be easier and results in the most elevated brownie ever!
Thanks Danielle for creating such a winner!
Thank you so much, Claire! So glad you loved the brownies!
I made these brownies for a friend of my son since kindergarten. She is 20 years old today. She took a cosmic brownie in her lunch box every day from kindergarten to high school. These brownies are a gourmet version on the original. They are easy to make and better than the original.
They were good brownies but they were more bitter than cosmic brownies so if you do this recipe just note that they don’t taste like the real thing but is still a good brownie recipe.
Very tasty! Will be making again ! Textures are spot on flavor spot on but minus all the chemical flavors 🫶🏻🫶🏻🫶🏻
Made this , the texture was spot on the brownie was spot on the ganache was very bitter recipe was followed exactly. I used Ghirardelli semi sweet baking chocolate. Should i use a different chocolate or perhaps milk chocolate?
The ganache isn’t meant to be super sweet, since the brownies themselves are pretty sweet. You can use milk chocolate but it does contain more milk, so I’d recommend reducing the cream just slightly.
These are PERFECT! So easy and turned out amazing. Thank you!!
I made these fot a space-themed party and they were a hit! Basically tasted like a fresh yummy version of the storebought ones. Sweet, chocolatey, and fudgy! They all got eaten and I was asked to make them again sometime. (I just used some small spherical rainbow sprinkles btw since I didn’t have candy-coated chocolates, and it still worked well)
Hi! How long should I let the brownies cool before adding the frosting? Also should I put the brownie base in the refrigerator to help cool down?
I would let the brownies cool completely before adding the ganache. You can put them in the refrigerator to speed up the process.
I made these, but found them to be really, really egg-y tasting. In the future, I would probably suggest only using two eggs and a yolk instead for anyone wanting to try this recipe!
Hi! It looks like a great recipe, but since I’m just making it for myself, I wanted to half the recipe. How would I go about halving the eggs/egg yolk? Thanks in advance!!
I’ve halved the recipe using 2 whole eggs and it worked great!
Could I refrigerate overnight before cutting the brownies?
Yes, that would be fine!
Thank you for such a delicious recipe! One taster said “I never tasted something so good, in my whole life.”
Is this considered a nut free dessert?
There aren’t any nuts in the recipe. I would use your best judgment though and check all of the ingredients that you use to make sure that they don’t contain any trace amounts of nuts as well.
Delicious, chewy, and fudgy – my favorite consistency of brownie! We all agreed they are better than the store-bought ones because they don’t have that processed/packaged taste. Really easy to make, though it looks like a lot of ingredients. We used chocolate chips for the ganache, simply because we had them on hand, and mini-m&ms because they were less expensive. The hardest part was waiting for them to chill! We chilled them for an hour, and the frosting was still a little soft, but chilling overnight set the frosting and made the brownies taste even better!!!
Thank you! So glad you loved the brownies, Christie!
Thanks for all you do, I wish to try out the chocolate cake recipe this weekend, hope it comes out like yours
Thank you! I hope you enjoy my chocolate cake recipe if you get a chance to try it!
This recipe makes me SMILE! I can’t wait to make these!
Question: You know how when you chop baking chocolate, it gets all static-y and flies everywhere? Do you have any tips to help that?
Thanks a bunch!
Christie
That happens to me occasionally, but I’m not sure of the best way to prevent it. Sometimes I’ll just buy the thinner chocolate bars (like Ghriradelli) and just break them into small pieces with my hands instead of chopping them!