In a stand mixer, combine 1 cup of melted salted butter, 1 cup of granulated sugar, and ½ cup of light brown sugar. Mix on medium speed for about 1 minute until smooth.

Add 2 teaspoons of vanilla extract and 2 large room-temperature eggs. Beat on low speed until just incorporated, about 30 seconds.

Add 2 cups of all-purpose flour, 1 tablespoon of corn starch, ½ cup of cocoa powder, 1 teaspoon of baking soda, and ½ teaspoon of kosher salt. Mix on low speed until combined.

Using a cookie scoop, portion out about 20 balls of dough onto a parchment-lined baking sheet. Cover and refrigerate for 30 minutes.

Preheat your oven to 350°F (175°C).

Bake the cookies for 9-10 minutes until edges are set but centers may be soft. Monitor closely.

Let the cookies cool on the baking sheet for about 3 minutes, then transfer to a wire rack to cool completely.

Heat ½ cup of heavy cream in a saucepan until simmering. Pour over 8 ounces of chopped semi-sweet chocolate and let sit for 5 minutes before stirring until smooth.

Spread the ganache over the cooled cookies and sprinkle with cosmic brownie sprinkles while still warm.