Preheat oven to 350 degrees F.
Line your cookie sheet with parchment paper or a silicone mat. Set aside.
In a large mixing bowl, use a hand mixer to combine the cake mix, thawed Cool Whip, egg, and vanilla extract.
Mix until all combined. You will have a thick and sticky dough. It’s ok. Don’t be tempted to add more dry ingredients.
Pour your powdered sugar into a shallow bowl or plate.
With a cookie scoop, scoop the dough and release it into the powdered sugar.
Roll the ball to coat it evenly with powdered sugar.
Place the coated cookie ball into your prepared cookie sheet. Make sure cookie balls are at least 1 ½ inches apart.
Repeat steps 6–8 until you have filled your cookie sheet.
Cook in a preheated oven for 8 to 10 minutes, or until they are set and the edges are golden.
Cool in the pan for 2 to 3 minutes, then carefully transfer to a cooling rack.