In a bowl of a stand mixer, cream together butter and sugar until light and fluffy, about 2 minutes. Add the eggs one at a time, beating after each addition, and extracts.

In a medium-sized mixing bowl, whisk together the flour, baking powder, and salt. *Note: weighing your flour is recommended.  If you don't have a food scale, use a large spoon to fluff your flour in its container first, and then lightly spoon it into the measuring cup, leveling with a knife.

Slowly add flour mixture to the creamed butter mixture a little at a time until fully incorporated.

Press the dough evenly into the prepared baking sheet. It helps to drop it by spoonfuls evenly all over, and then press down with clean hands.  Place a piece of parchment on top and then use your hand to smooth it out as even as possible.

Bake for 20-25 minutes.  Ideally, you should remove from oven before it starts turning golden brown.  You may see slight browning on the very edges, but the center should look pale, but set.

Remove from oven and allow to cool completely.

While the cookie bars are cooling, prepare the frosting. Whip the butter until light and fluffy and slowly add powdered sugar a bit at a time until incorporated.

Add extracts.  Very slowly, add a little bit of milk at a time until desired consistency is reached. If desired, add a few drops of food coloring.

When the pan of cookies is completely cool, spread with frosting and sprinkle with colored sprinkles immediately.

Cut into squares. The number of bars this makes will depend on how big you cut the squares, but these are VERY rich and you can get away with cutting these into 40+ servings!