Step 1

Preheat the oven to 350°F and line a 9x13 baking dish with parchment paper. Set aside.

Step 2

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

Step 3

In a large mixing bowl, cream together the softened butter, brown sugar, and white sugar with a hand mixer until light and fluffy.

Step 4

Add in the eggs, one at a time, mixing until incorporated.

Step 5

Add in the vanilla and mix until just combined.

Step 6

Gradually add in the flour mixture, scraping down the sides as needed. The dough will be thick.

Step 7

Use a spatula to fold in the M&Ms, white chocolate chips, and sprinkles until evenly distributed.

Step 8

Press the dough evenly into the prepared pan, topping with additional M&Ms, white chocolate chips, and sprinkles.

Step 9

Bake for 22-28 minutes or until the edges are golden and a toothpick inserted into the center comes out clean.

Step 10

Move the pan to a wire rack to cool for at least 30-60 minutes before slicing into bars.