Preheat your oven to 350°F (175°C) and grease a 9x13 inch baking pan.

In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.

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

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

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

Fold in the white chocolate chips, red and blue M&M's, and sprinkles until evenly distributed.

Spread the cookie dough evenly in the prepared baking pan.

Bake in the preheated oven for 25-30 minutes, or until the edges are golden and a toothpick inserted in the center comes out clean.

Remove from the oven and let cool in the pan for about 10 minutes, then transfer to a wire rack to cool completely before cutting into bars.