Rainbow Brownies
Get the nostalgic taste of chewy, fudgy Cosmic Brownies with our easy homemade Rainbow Brownie recipe. Perfect for lunchboxes, these dense chocolate bars with a soft texture and perfect frosting are topped with rainbow chips for a fun crunch.
Servings: 18 Brownies
Calories: 309kcal
Ingredients
Brownie Base
- 7 oz dark chocolate chopped (about 1¼ to 1½ cups), 2 of the 3.5 oz bars, 72% cocoa
- ¾ cup salted butter (1 1/2 sticks)
- 3 large eggs
- 1 cup granulated sugar
- ½ cup light brown sugar tightly packed
- 1 teaspoon vanilla extract
- ¾ cup all-purpose flour
- 2 tablespoons unsweetened Dutch process cocoa powder
Chocolate Frosting
- 2 cups powdered sugar
- ¼ cup unsweetened Dutch process cocoa powder
- 4 tablespoons salted butter
- 3 tablespoons hot water
- Rainbow chocolate chips or rainbow sprinkles for decoration
Instructions
Brownies
- Preheat oven to 350°F.
- Spray a 9x13-inch cake pan with non-stick spray, then line with parchment paper, allowing some overhang for easy removal. Spray the parchment paper with additional non-stick spray.
- In a heatproof bowl set over simmering water (double boiler style), melt the chopped chocolate and butter, stirring until smooth. You can also microwave in 30-second bursts, stirring between each. Set aside
- In a large mixing bowl, combine eggs, granulated sugar, and brown sugar. Beat on medium-high speed (hand or stand mixer) for 2 to 3 minutes, until lighter in color and slightly thickened.
- Pour in the chocolate mixture, along with the vanilla and mix until incorporated.
- Sift the flour and cocoa into the batter and mix on low speed just until smooth and lump-free.
- Spread the batter evenly in your prepared pan.
- Bake for 20 to 25 minutes, checking at 20 minutes. The edges should be set, and a skewer inserted should come out with a few moist crumbs.
- Let the brownies sit for 5 minutes before icing.
Chocolate Frosting
- Sift the powdered sugar and cocoa powder into a medium or large bowl.
- In a microwave-safe bowl or glass measuring cup, heat the butter and water together just until the butter melts.
- Pour over the dry ingredients and stir until smooth. Use a whisk or mixer if needed.
Assembling the Brownies
- Spread the warm frosting over the warm brownies, using an offset spatula or the back of a spoon to smooth it out as it begins to melt slightly against the surface.
- After 1–2 minutes, top with rainbow sprinkles or chocolate chips before the frosting sets.
- Chill in the fridge for at least a few hours or overnight until fully set.
- Lift out using the parchment, slice with a sharp knife, and store in an airtight container in the fridge for up to 5 days.
Nutrition
Serving: 1Brownie | Calories: 309kcal | Carbohydrates: 41g | Protein: 3g | Fat: 16g | Saturated Fat: 10g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 4g | Trans Fat: 0.4g | Cholesterol: 58mg | Sodium: 97mg | Potassium: 134mg | Fiber: 2g | Sugar: 33g | Vitamin A: 363IU | Calcium: 24mg | Iron: 2mg
