Preheat the oven to 350 F. In a large bowl, mix together butter, peanut butter, and powdered sugar until smooth. Add in the vanilla extract and flour until combined.
Fold in the chocolate chips and Reese's pieces. Roll the cookie dough into balls and place onto a large ungreased baking sheet. Bake for 10-12 minutes. Place the remaining powdered sugar into a shallow dish.