Cream together butter and sugar until smooth. Beat in eggs and vanilla. Stir in flour, baking powder and salt. Cover and chill 1 hour or longer.
For stained glass. Put hard candy, such as jolly ranchers or life savers, in plastic bags. (separate the colors you are wanting to use.) Take a hammer or rolling pin and crush the candy inot little pieces.
Preheat oven to 400* F. Roll out dough on floured surface 1/4 - 1/2 inch in thickness. Cut into shapes. Cut middle of cookie to allow for candy.
Place cookies on an ungreased foil lined cookie sheet. Fill middle cut outs with one or more color of candy pieces.
Bake 6 - 8 minutes. Watch closely so they don't brown.
Cool completely and they should remove easily from foil.