Preheat oven to 375˚F

In a mixing bowl beat butter and peanut butter with electric mixer set to medium speed for 30 seconds or until blended. Add 1/2 cup flour, sugars, egg, baking soda and baking powder and vanilla. Beat until thoroughly combined. Add remaining flour and continue blending until all is well combined. Add the (optional) chopped peanuts  and mix completely.
Cover and chill dough for 1 hour for easy handling.

Shape dough into 1-inch balls. Place each 2 inches apart on an ungreased cookie sheet. Flatten each ball by pressing down with tines of fork. Make a crisscross pattern with fork.

Place in oven for 7 to 9 minutes or until bottoms are lightly brown.