Heat the oven to 350 degrees F and prepare a 9x13" pan by spraying with cooking spray.

In the bowl of an electric mixer, cream together the butter and sugar until it's light and fluffy, for about 2-3 minutes.

Add the eggs, one at a time, mixing after each egg. Then add the vanilla and mix to combine.

In a separate bowl, combine the dry ingredients. Slowly add the dry ingredients to the sugar/butter mixture, mixing until just combined. Then, fold in the sprinkles.

Spread the cookie batter into the pan, patting it down so it's evenly spread. Add more sprinkles on top, if desired.

Bake for 15-18 minuts, until the edges are lightly golden. The bars will look pale and puffy and under cooked, but be sure to not over-bake them. Let them cool completely before cutting and serving.