In a KitchenAid stand mixer, cream together the butter and sugars. Then add the vanilla extract and egg and mix until combined. Then add the flour, baking powder, and salt. Mix until a soft dough forms. Stir in your mix in ingredients. Cover and refrigerate for 1 hour or overnight.
If you don't plan to bake your cookies within a day or two you can freeze the prepared dough for use later.