In a large bowl, cream together butter and sugar until smooth. Beat in eggs and vanilla. Stir in the flour, baking powder, and salt. Cover, and chill dough for at least one hour (or overnight).
Preheat oven to 400 degrees Fahrenheit (200 degrees Celsius). Roll out dough on floured surface 1/4 to 1/2 inch thick.
Grease cookie mold with margarine or shortening. Press the dough firmly into the mold, so the pattern will shape the cookies. Bake at 400 degrees 6 to 8 minutes in preheated oven. Cool completely.