Preheat the oven to 350 F. In a large bowl, mix together cake mix, eggs, vegetable oil, and peanut butter until smooth. Fold in the Reese's pieces.
Place the powdered sugar into a shallow dish. Roll the cookie dough into balls, and roll each one into the powdered sugar. Place the cookies onto a large ungreased baking sheet at least 2-inches apart. Bake for 10-12 minutes.