In the bowl of a stand mixer (or using an electric hand mixer), cream together the butter and sugar and whip until well combined. Then, add the egg yolks and extracts and mix until also well combined.
Combine and mix together flour, baking powder and salt in a medium sized mixing bowl. Add in batches to the wet ingredients, mixing just until combined.
Then, add the sprinkles and mix until just combined.
Divide the dough in half and roll between two pieces of parchment paper using a rolling pin, until the dough is about 1/4 inch thick. Cut out shapes using cookie cutters. (I take the excess dough and roll up and re-roll until I have no dough left).
Place on a silicon mat or parchment paper lined baking sheet and bake for about 5 minutes (or longer for bigger shapes).
Make royal icing and color the icing. Pipe outlines and then flood the cookies. Allow for them to dry overnight.