Preheat oven @ 160 degrees C, [315 degrees F] Combine sugars, add melted butter, vanilla & peanut butter, lightly beaten egg, mix well.
Gradually add sifted flour until thoroughly mixed batter forms. Refrigerate for 30 mins.
2 tablespoons of batter at a time on lined baking trays & flatten using a fork, or press to flatten using hands to shape.
Bake for 15 mins or until golden brown. Rack cool before serving.