Preheat oven to 400 degrees.
Cream together butter and sugar until smooth.
Add eggs and vanilla, beat until combined.
Sift flour, baking powder and salt then add to mixture.
Stir until combined.
Cover and cool in fridge for at least an hour.
Flour surface, knead dough and roll out.
Cut into circle shapes, place on cookie sheet and bake for 6-8 minutes.
Allow to completely cool before icing.
Beat on medium speed for 7-10 minutes. At this point the icing will be pretty stiff. Divide and place in air tight containers.
Add food coloring if desired (the gel high concentrated kind).
Thin out the icing to desired consistency with water as needed.
Make sure to keep covered to avoid drying out.