Preheat the oven to 350°F (175°C).
In a bowl, cream together the butter and sugar.
Add the eggs and vanilla, mixing well.
In another bowl, combine flour, baking powder, and salt.
Gradually add the dry ingredients to the wet mixture.
Chill the dough for 30 minutes.
Roll out the dough and cut into desired shapes.
Place on a baking sheet and bake for 10-12 minutes.
Let cool completely before decorating.
Decorate with royal icing as desired.