In a bowl, stir together flour & baking powder. Set aside.
In mixer bowl, beat together butter & sugar until fluffy.
Beat in eggs & vanilla.
Stir in flour mixture, a third at a time to make stiff dough.
Preheat oven to 350 degrees
Scoop a ball of dough, roll into a ball & roll in sugar to coat.
Bake on non-stick cookie sheet for 8 minutes
Cool completely on pan before transferring to a wire rack
In a small bowl, mix sugar & water to form a thick, smooth icing. Adding more sugar as needed.
Stir in food coloring to desired shade.
Transfer to piping bag & decorate as desired.
Let dry completely before stacking