Preheat oven to 350 degrees and spray a 9×13 baking pan with baking spray.

In a large mixing bowl, add the cocoa powder to the melted butter and mix until smooth.

Mix in the sugars, eggs, and vanilla.

In a separate bowl mix together the flour, cornstarch and the pinch of salt.

Then gradually mix it into the wet ingredients until just smooth.

Pour the brownie batter into the prepared pan, spread it around the whole pan and bake for 18 minutes.

To achieve that fudgy, chewy texture that cosmic brownies are known for, be careful not to overbake them. Keep an eye on them towards the end of the baking time and remove from the oven when the edges are set but the center is still slightly gooey.

Cool completely.

To make the chocolate ganache frosting, add chocolate chips and heavy cream to a large microwave safe dish and melt in 30 second intervals, let the melted chocolate rest for a couple of minutes and then stir until smooth.

Smooth the rich chocolate ganache over brownies with a rubber spatula and sprinkle rainbow chip sprinkles while ganache is still wet.

For best results, allow your cosmic brownies to cool completely in the pan before slicing and serving. This helps them set up properly and prevents them from falling apart when you cut into them.