Combine butter and brown sugar with electric mixer until fluffy
Beat in egg and vanilla
In a separate bowl, combine flour, baking powder, and salt
Add flour mixture ½ cup at a time
Blend thoroughly
Knead into a ball, and refrigerate for 2-3 hours
Preheat Oven to 325 degrees F
Roll dough on a lightly floured surface
Cut into shapes with cookie cutter
Bake 12 minutes
Cool on rack
Decorate and/or Eat