This Cosmic Brownie recipe from scratch is irresistible: fudgy, chewy, and easy to make. If you love rich chocolate, this copycat version of the classic lunchbox treat is sure to become a favorite.
Homemade cosmic brownies
Cosmic brownies bring back childhood memories. This copycat recipe improves on the original with a denser, more chocolate-forward brownie and a glossy chocolate glaze topped with colorful candy pieces. Despite their impressive appearance, these brownies are straightforward to prepare and forgiving for home bakers.
What are Cosmic Brownies?
The original Cosmic Brownie debuted in the 1960s, known for its fudgy chocolate base, chocolate icing, and rainbow candy-coated chocolate chips on top. This homemade version recreates that nostalgic flavor and texture with fresher ingredients and a slightly more indulgent glaze.
Ingredients You’ll Need
- Granulated sugar, light brown sugar, vanilla, eggs, and egg yolks — the base that provides structure, sweetness, and chewiness.
- Butter — adds richness and helps carry the chocolate flavor.
- Semisweet chocolate chips — melted with butter to create a deeply chocolatey, fudgy batter.
- Vegetable oil — keeps the brownies moist.
- Self-rising flour — provides gentle lift so the brownies stay dense but not flat.
- Cocoa powder — deepens the chocolate flavor.
For the glaze
- Sweetened condensed milk — sweet and silky, it helps make a smooth glaze.
- Semisweet chocolate chips — melted into the condensed milk for a shiny chocolate topping.
- Butter — softens the sweetness and helps the glaze set smoothly.
Topping
- Rainbow chocolate chips — classic, nostalgic, and colorful on top of the glaze.
Step 1: Preheat the oven to 350°F. Prepare a 9-by-13-inch baking pan with parchment paper or baking spray. Gather your ingredients.
Step 2: In a large bowl, whisk together granulated sugar, light brown sugar, whole eggs, egg yolks, and vanilla until just combined. Avoid overmixing to keep the brownies dense and fudgy instead of cakey.
Step 3: In a microwave-safe bowl, combine chocolate chips and butter. Microwave in 30-second intervals, stirring between each interval until fully melted and smooth. Allow the mixture to cool to room temperature before adding it to the egg-sugar mixture to prevent the eggs from cooking.
Step 4: Stir the melted chocolate mixture into the sugar-egg mixture. Add vegetable oil, then gently fold in self-rising flour and cocoa powder until just combined. Pour the batter into the prepared pan and bake 30–35 minutes. Pull the brownies from the oven when a toothpick inserted in the center comes out with a few moist crumbs — they will continue to set as they cool.
Step 5: While the brownies bake, make the glaze. In a microwave-safe bowl, combine softened butter and sweetened condensed milk, heating in 30-second intervals and stirring between each. Add semisweet chocolate chips and stir until the glaze is smooth. If needed, microwave an additional 15 seconds to finish melting.
Pour the warm glaze over the cooled brownies, then immediately sprinkle the rainbow chocolate chips across the top. Refrigerate until the glaze sets. Slice into squares and serve.
How to store cosmic brownies
Store cut brownies in an airtight container at room temperature for 3–4 days. If you want to keep them fresher longer, leave them uncut in the pan and wrap tightly with plastic wrap for 4–5 days. Refrigerate for up to 7 days or freeze for up to 3 months. Thaw frozen brownies overnight in the refrigerator. Warm individual pieces in the microwave or in a 350°F oven if you prefer them warm.
How will I know when the brownies are done?
Insert a toothpick into the center. If it comes out with several moist crumbs, remove the pan — the brownies will continue to set as they cool. A completely clean toothpick indicates the brownies may be overbaked and dry.
Why didn’t my brownies cut into neat squares?
Cut brownies only after the glaze has fully set and the brownies are completely cool. Cutting while still warm causes crumbs and uneven edges.
Variations
- Add chopped nuts such as walnuts or pecans for crunch.
- Swap the rainbow chocolate chips for M&M’s, colorful sprinkles, or crushed cookies for a different texture or look.
Cosmic Brownie Recipe (Ingredients & Instructions)
Cosmic Brownie Recipe {Easy & Delicious}
Ingredients
Brownie
- 1 cup granulated sugar
- 1 cup light brown sugar
- 2 tsp vanilla extract
- 2 eggs
- 2 egg yolks
- 1 stick butter, melted
- 1 1/3 cups semisweet chocolate chips
- 1/2 cup vegetable oil
- 1 1/4 cups self-rising flour
- 1/4 cup cocoa powder
Glaze
- 4 tbsp butter, softened
- 1/2 cup sweetened condensed milk
- 1 1/3 cups semisweet chocolate chips
Topping
- 1/4 cup rainbow chocolate chips
Instructions
- Preheat the oven to 350°F. Spray a 9-by-13-inch pan with baking spray or line with parchment.
- Combine granulated sugar, light brown sugar, vanilla, whole eggs, and yolks in a large bowl; mix until just combined.
- Place semisweet chocolate chips and butter in a microwave-safe bowl. Microwave in 30-second intervals, stirring between each, until melted and smooth. Let cool slightly.
- Pour the chocolate mixture into the sugar-egg mixture and stir until combined. Add vegetable oil, then fold in self-rising flour and cocoa powder until just combined.
- Pour batter into the prepared pan and bake 30–35 minutes. A toothpick should come out with moist crumbs. Remove from oven and let cool.
Glaze
- Place chocolate chips in a medium bowl and set aside.
- Combine sweetened condensed milk and softened butter in a microwave-safe bowl. Microwave in 30-second intervals, stirring between each, until the butter is melted.
- Add the chocolate chips and stir until smooth. If necessary, microwave an additional 15 seconds.
- Pour the glaze over the cooled brownies and immediately sprinkle with rainbow chips.
- Let the glaze set completely before slicing. Enjoy!
