Preheat the oven to 350℉. Line baking sheets with parchment paper.
In a medium mixing bowl, use an electric hand mixer to combine the cake mix, Cool Whip and egg just until combined. Put the powdered sugar into a small bowl.
Use a cookie scoop to scoop out the dough and place it into the bowl with the powdered sugar. Then roll the dough in the powdered sugar without touching it with your fingers. You don't want your fingers to become red from the cookie dough. Place the cookies on the prepared baking sheet about 2-inches apart.
Bake the cookies 14 to 16 minutes, until the edges are firm.