1Heat oven to 350°F. Spray cookie sheet with cooking spray.
2In medium bowl, stir together cake mix, whipped topping and egg until combined. (Dough will be thick and sticky.)
3Place powdered sugar in small bowl. Using wet hands, shape tablespoonfuls of dough into balls; roll in powdered sugar. On cookie sheet, place balls 2 inches apart.
4Bake 10 to 12 minutes or until edges are set. Cool 2 minutes; remove from cookie sheet to cooling rack.