In a large bowl, cream the butter, peanut butter and sugars. Add the vanilla and egg, beating until light and fluffy. Stir together flour, baking soda, baking powder and salt and add to butter mixture, blending thoroughly. Shape into 1 inch balls and place about 2 inches apart on a baking sheet. Flatten with fork tines in a criss cross pattern. Bake at 350 degrees for 10 minutes or until lightly browned. Makes 4 dozen cookies.