1In a medium bowl, cream the butter, peanut butter and sugar together. Stir in vanilla and flour, mix well. Then stir in pecans. Cover dough and chill for 3 hours or overnight.
2Preheat oven to 325 degrees F (165 degrees C).
3Roll cookie dough into walnut sized balls and place them on an unprepared cookie sheet. Bake for 15 to 20 minutes in the preheated oven. Cool slightly, then roll in confectioners' sugar.