Preheat oven to 400º.
Cream butter, powdered sugar, egg & vanilla.
Sift flour, baking powder & salt.
Blend dry ingredients into creamed mixture.
Chill dough for 1 hour.
Roll chilled dough 1/4 thick, cut with cookie cutters and place on cooking sheet.
If desired, sprinkle with colored sugar, or other cookie sprinkles, or leave plain for frosting.
Bake @ 400º for 6-8 minutes for small cookies, 8-10 minutes for larger cookies.
Frost when cool.