Preheat oven to 350°F and line a 9×13 baking dish with parchment paper, all the way up the sides.

Melt butter and let it come to room temperature.

In a medium sized bowl, combine the flour, baking powder and salt together.

In a mixing bowl fitted with a paddle attachment, combine the melted butter, brown sugar and sugar. Then add the eggs and vanilla. Gently fold in the flour mixture, then fold in the M&M’s and sprinkles.

Spread batter into the lined baking dish and smooth the top (it will be thick). Sprinkle more sprinkles and M&M’s on top. Bake for 20-25 minutes or until lightly golden on top, rotating pan halfway through baking. The middle will still be a little gooey but they will continue to bake even after you take them out of the oven. Do not over-bake or they will be dry! Remove from oven and let cool completely before cutting into squares.