These Cosmic Brownie Cookies are soft, chewy, and out-of-this-world delicious. Topped with a rich chocolate ganache and colorful rainbow crunch sprinkles, they are the ultimate nostalgic treat to satisfy your sweet tooth!
Preheat oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a large bowl, whisk together the melted butter, granulated sugar, and brown sugar until smooth.
Add the egg and vanilla extract, whisking until fully combined.
Stir in the flour, cocoa powder, cornstarch, baking soda, and salt until a soft dough forms.
Scoop the dough into 12 equal-sized balls and place them on the prepared baking sheet, spacing them about 2 inches apart.
Bake for 10 to 12 minutes, until the edges are set but the centers are still soft. Let cool completely on the baking sheet.
To make the ganache, heat the heavy cream in a microwave-safe bowl until simmering, then pour over the chocolate chips. Let sit for 2 minutes, then whisk until smooth.
Spoon the chocolate ganache over each cooled cookie and immediately top with candy-coated rainbow chocolate chips. Allow the ganache to set before serving.
Notes
Store cookies in an airtight container at room temperature for up to 3 days, or refrigerate for up to a week.