Preheat your oven to 350°F (175°C). Grease a 9x13 inch baking pan or line it with parchment paper for easy removal.
In a large mixing bowl, combine the melted butter and granulated sugar. Stir until well blended.
Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.
In a separate bowl, whisk together the flour, cocoa powder, salt, and baking powder. Gradually add the dry ingredients to the wet mixture, stirring until just combined.
Fold in the white chocolate chips and half of the red and blue sprinkles.
Pour the brownie batter into the prepared baking pan, spreading it evenly. Sprinkle the remaining red and blue sprinkles on top.
Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs.
Allow the brownies to cool in the pan for at least 15 minutes before cutting into squares.