Preheat the oven to 375° F.
Whisk together flour and baking powder.
In a separate large bowl, cream together butter, sugar, and brown sugar.
Mix in the egg, peanut butter, and vanilla to the butter/sugar mixture.
Slowly stir in the flour until the mix is well blended (the dough should be thick enough to handle by hand).
Shape the dough into one inch balls and arrange on the cookie sheet about two inches apart.
Press flat with a fork (See process for more details).
Bake for approximately 10 to 12 minutes.
Allow to cook on a rack.
Enjoy!!