1. Preheat your oven to 350°F (175°C).

2. In a large bowl, cream together the melted butter, granulated sugar, and brown sugar until light and fluffy.

3. Beat in the eggs one at a time, then stir in the vanilla extract.

4. In a separate bowl, whisk together the flour, cocoa powder, salt, and baking powder.

5. Gradually add the dry ingredients to the wet ingredients, mixing until *just* combined.

6. Grease and flour an 8×8 inch baking pan.

7. Pour the brownie batter into the prepared pan and spread it evenly.

8. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs attached.

9. Let the brownies cool completely in the pan before frosting.

10. Place the chocolate chips in a heat-safe bowl.

11. In a small saucepan, heat the heavy cream over medium heat until it just begins to simmer.

12. Pour the hot cream over the chocolate chips and let it sit for a minute to soften the chocolate.

13. Gently whisk the mixture until smooth and glossy.

14. Once the brownies are completely cool, spread the chocolate ganache evenly over the top.

15. Immediately sprinkle generously with rainbow sprinkles.

16. Let the ganache set for about 30 minutes before cutting the brownies into squares.

17. For clean cuts, use a warm knife (dip in hot water and wipe between cuts).