Homemade Cosmic Brownies
Featuring a rich brownie base, a fudgy chocolate glaze, and a scattering of candy-coated rainbow chips, this copycat Cosmic Brownie recipe takes everything you love about the classic and makes it 100 times better!
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Servings: 16 brownies
Ingredients
For the cosmic brownie base
- 10 tablespoons unsalted butter
- ¼ cup cocoa powder, preferably dutch-processed
- A pinch espresso powder (optional)
- ¾ cup granulated sugar
- ¼ cup light brown sugar
- 1 teaspoon vanilla extract
- 2 large eggs
- 1 egg yolk (optional)
- 1 tablespoon light corn syrup (optional)
- 4 ounces chopped milk or semisweet chocolate
- ⅔ cup all-purpose flour
- 1 tablespoon cornstarch
- 1 teaspoon kosher salt
For the ganache topping (Option 1)
- 2 ounces chopped semisweet chocolate
- 2 ounces chopped milk chocolate can substitute with more semisweet chocolate and vice versa
- ¼ cup heavy cream
- A pinch of salt
For the traditional fudge topping (Option 2)
- ¾ cup granulated sugar
- 1 tablespoon unsweetened cocoa powder
- 6 tablespoons whole milk
- ¾ ounce unsweetened chocolate
- A pinch of salt
- A dash vanilla extract
- 2 tablespoons unsalted butter, cubed
Instructions
To make the cosmic brownies:
- Preheat the oven to 325°F, then lightly grease and line a 9×9 square baking pan with parchment paper.
- In a large bowl, sift together the ⅔ cup flour, 1 tablespoon cornstarch, and 1 teaspoon salt. Set aside.
- In a medium bowl, heat the 10 tablespoons of butter in 30 second increments until melted and very hot (be careful not to let the butter pop or explode).
- Whisk in the ¼ cup cocoa powder and pinch of espresso powder until well combined, then set aside to bloom for at least 5 minutes.
- Add the ¾ cup granulated sugar and ¼ cup brown sugar to the butter, whisking until well incorporated and very smooth, around 2 minutes.
- Crack in the eggs one at a time followed by the egg yolk, then add 1 teaspoon of vanilla extract and 1 tablespoon corn syrup. Whisk until smooth.
- In a separate small bowl, heat the 4 ounces of chocolate in the microwave or over a double boiler, stirring every 30 seconds until melted. Allow the chocolate to cool slightly before adding to the egg and sugar mixture. Mix until homogeneous.
- Using a rubber spatula, fold in the dry ingredients until just combined and no streaks of flour remain. Pour the brownie batter into the prepared pan—it will be thick, so use an offset spatula or knife to spread it into an even layer.
- Bake for 35-40 minutes or until the brownies are puffed and set in the middle; if you insert a toothpick into the center of the pan, a few moist crumbs should stick to it, but not raw batter (the brownies will continue to cook and set as they cool).
- Remove the brownies from the oven, then carefully bang the pan on the counter a few times to deflate and flatten the top. Set aside to cool completely.
- In the meantime, make the cosmic brownie glaze; the ganache topping option is very easy and rich-tasting but will stay soft at room temperature. The fudge frosting option requires more technical skill but has an authentic Cosmic brownie taste and stays firm at room temperature.
To make the ganache topping (Option 1):
- Place the 2 ounces of chopped milk chocolate, 2 ounces of chopped semisweet chocolate, and a pinch of salt into a heat-safe bowl and set aside.
- To make the ganache, heat the ¼ cup cream in a small saucepan over medium heat until it begins to gently simmer. Alternatively, you can heat the cream in the microwave for 30 to 60 seconds.
- Immediately pour the cream over the chocolate, making sure that each piece is submerged. Let the bowl stand for 2 minutes to soften, then stir with a silicone spatula until smooth.
- Pour the ganache over the cooled brownies and use an offset spatula or knife to spread into an even layer. Sprinkle over the candy-coated rainbow chips.
- Refrigerate the brownies for 1 to 2 hours, or until the ganache is set, before lifting out of the pan.
- Use a sharp knife to slice the brownies into 8 even pieces (for traditional Cosmic Brownie bars) or 16 even squares (for smaller brownies).
- Cosmic brownies with ganache are best stored in the fridge, since the topping will remain soft at room temperature. The brownies will last up to 3 days at room temperature or in the fridge for 1 week.
To make the fudge frosting (Option 2):
- In a small saucepan, melt the ¾ cup granulated sugar, 1 tbsp cocoa powder, 6 tablespoons whole milk, salt, and vanilla over low heat until the sugar is dissolved, around 5 minutes.
- Bring the mixture to a boil and cook without stirring for one minute. As the mixture cooks, brush down the sides of the pan with warm water and a pastry brush to dissolve any sugar crystals, then turn off the heat.
- Add in the chocolate (¾ ounce) and stir until melted and smooth.
- Place the pan back over medium heat. Without stirring, cook the chocolate mixture until it registers 238℉ on a candy thermometer, around 10 minutes. Continue to brush down the sides of the pan with water as necessary to prevent the fudge from crystallizing.
- Immediately pour the fudge mixture into a clean bowl and top with the 2 tablespoons of cubed butter, but do not stir. Let the fudge cool at room temperature until it reaches 120 to 130℉, around 20 minutes.
- Once cooled, use a wooden spoon or spatula to beat the mixture for 3 to 5 minutes, until the butter is fully incorporated and a thick, glossy, fudge glaze has formed and is just beginning to lose its sheen.
- Immediately pour the fudge topping over the cooled brownies and use an offset spatula or knife to spread into an even layer. Quickly sprinkle over the candy-coated rainbow chips, as the frosting will set quickly.
- Let the brownies sit at room temperature until the frosting is fully set before lifting out of the pan.
- Use a sharp knife to slice the brownies into 8 even pieces (for traditional Cosmic Brownie bars) or 16 even squares (for smaller brownies).
- Cosmic brownies with fudge topping are best stored in an airtight container at room temperature for up to 3 to 4 days, though they will last in the fridge for up to 1 week.