These thick, fudgy homemade cosmic brownies are a spin on my viral cosmic brownies, but 10x better than storebought! Topped with a creamy white chocolate ganache and decorated for the 4th of July, these will be the cutest dessert at the party!

video
Watch me make this on Instagram!
Watch me make this on Instagram! You'll see how easy it is to make this xxx
Links seen in the video
- Sprinkle Mix
- Melting Wafers (this link will get you 20% off at Cambie - use the search bar to find "Merckens super white")
- Giant Knife
- Wilton #10 for the red lines
- Tipless piping bags
- Pre-Cut Parchment Sheets
- 9x13" Pan
For the treat bags:
Tips & Tricks
- Be sure to stir well between each microwave interval when melting the white chocolate. This helps distribute the heat evenly and prevents hot spots that can cause the chocolate to seize.
- This does create a fairly thick layer of white chocolate on top, but I've found this amount is necessary to fully cover the brownies without them showing through. Plus, it makes them extra decadent!
- Add the sprinkles immediately after spreading the ganache, as it firms up quickly.
- For gifting, place each brownie in a jumbo muffin liner, slip it into a cello bag, and finish it off with one of the gift tags included in my Crafty Bakers Club!

Red, White, and Blue Cosmic Brownies
Makes: 12
These thick, fudgy homemade cosmic brownies are a spin on my viral cosmic brownies, but 10x better than storebought! Topped with a creamy white chocolate ganache and decorated for the 4th of July, these will be the cutest dessert at the party!
Ingredients
⭐️ Before you begin! If you make this, will you do me a huge favor afterwards and leave a review and rating letting me know how you liked this recipe? This helps my small business thrive so I can continue providing free recipes and high-quality content for you.
Instructions
- Preheat oven to 350° F.
- In a large microwave-safe bowl, add ¾ cup unsalted butter, 1 ½ cups granulated sugar, and ½ cup light brown sugar. Microwave for 2 minutes, stir, then microwave for 30 more seconds. Carefully remove bowl from microwave and stir until smooth. Let cool for 2-3 minutes.
- To the butter and sugar mixture, stir in the 3 large eggs + 1 egg yolk, 1 tablespoon vanilla extract, 1 teaspoon salt, ¼ teaspoon baking soda, and 2 tablespoons cornstarch. Once combined, mix in 1 ½ cups Hershey's cocoa powder (100% cacao natural unsweetened) and 1 cup all-purpose flour until just combined (I recommend mixing by hand to prevent from overmixing). Stir in ¼ cup vegetable oil.
- Spray a light metal 9x13 pan with nonstick cooking spray, then press on a piece of parchment paper to cover the bottom and long sides to create a parchment sling (photo in post above!). This will help you lift the brownies out of the pan so that you can cut them nicely. Spread brownie batter into the prepared pan until smooth.Note: baking these in glass or dark metal pans may cause them to overbake and become bitter. If that's the only pan you have, lining with parchment on all sides becomes more crucial. You will also likely need to bake them for less time to prevent overbaking.
- Bake at 350° F for 24-26 minutes or until center looks set and no longer jiggles when you gently shake the pan (do not overbake). Let cool completely in pan (once the pan is no longer hot to the touch, you can speed up cooling by placing pan in refrigerator.
To Make White Chocolate Ganache
- In a medium-sized bowl, place 15 ounces white melting wafers or high-quality white chocolate. Set aside.
- In a medium-sized bowl or liquid measuring cup, heat ⅓ cup heavy cream in the microwave for 30-60 seconds, or until it begins to bubble. You can also heat this on the stove; remove it once it begins to steam.
- Use a hot pad to carefully remove the heavy cream from the microwave and pour over the white chocolate melting wafers. Allow to sit for 30 seconds, then stir. Microwave in 20 second increments until fully melted, stirring in between each increment (super important!). Mix until smooth (this can take a minute or two to come together). The ganache will be on the thicker end, which is what we want.
- If you want to make the white chocolate less yellow, dip the tip of a toothpick in purple food coloring and add tiny swipes until the color is more neutral.
- Pour over cooled brownies, quickly spread until smooth, then immediately top with blue star sprinkles. Cover and refrigerate for 1-2 hours for ganache to firm up.
- Once the ganache is firmed up, let the pan sit out for about 1 hour before cutting. This will help so that the topping doesn't crack when you cut it. Then, use a large knife to slice bars.
To Decorate:
- In a medium-sized bowl, mix together 1 ½ cup powdered sugar, 2 tablespoons warm water, and 1 teaspoon light corn syrup. Stir until smooth and thick. It should hold it's shape when drizzled. If too thin, add 1-2 tablespoons more powdered sugar. Color with red food coloring and place in a piping bag with a small round tip (I used a Wilton 10).
- Pipe red wavy lines to mimic the Little Debbie version and allow the icing to firm up before packaging.
- Store in an airtight container for 3-4 days. They get even better & fudgier on Day 2!
Notes from Melissa
Cocoa Powder: I tested this recipe using Hershey's Unsweetened Cocoa powder, as it's my favorite cocoa for brownies. Take note that different brands may cause the brownie taste and texture to be a bit different.
Nutrition is just an estimate and calculated with an automated system.

