Preheat oven to 325 degrees
Sift together the flour, baking soda and salt
Cream butter,peanut butter, white and brown sugars.
Mix in egg and 1/2 teaspoon of vanilla.
Stir the flour mixture into the creamed mixture.
Shape the dough into 48 balls, 1 inch each. place each ball into one compartment of a mini muffin tin.
Bake for 14-16 minutes or until lightly browned.
Remove from oven and immediately make wells in the center of each using a melon baller (I used an oven thermometer).
Cool in pan for 5 minutes then carefully remove to wire racks.