Preheat the oven to 350℉ and line a baking sheet with parchment paper.
Place the powdered sugar in a shallow bowl, and set aside. You'll dust the cookies with this later.
To a large mixing bowl, add the cake mix and egg. Whisk well to combine. Add the Cool Whip to the bowl and stir with a mixing spatula to combine.
Using a medium cookie scoop or table spoon, scoop about 2 tablespoons of dough. Add to the bowl of powdered sugar and roll it through, to coat. Use your hands to form dough into a ball. *Don't try to form the dough ball without powdered sugar, it will be too sticky.
Arrange the dough balls in a single layer on the prepared baking sheet, leaving 2 to 3 inches of space between each.
Bake in preheated oven for 8-10 minutes, until the tops of the crinkle cookies are puffy and are starting to crack. *They will look unfinished at first - this is normal. They'll finish baking as they cool.
Remove from the oven and let the cookies cool on the cookie sheet for 5-10 minutes. Transfer to a wire rack to cool completely.
Notes
Don't over mix the batter. If you whip the ingredients together too much, the cookies may fall flat. This is why it's best to mix the ingredients with a spatula and bowl rather than using an electric mixer.
Expect the cookie batter to be loose and sticky. It will look strange when first mixing it. Keep going, the batter will eventually thicken. The batter will be very sticky, but this is ok!
Use a lot of powdered sugar when rolling. Make sure to generously coat these cookies in powdered sugar. This will help make sure they don't stick to the parchment paper when baking.
Feel free to use any brand of chocolate or Devils food cake mix. If you want a different type of crinkle cookies, you can swap the chocolate for lemon, red velvet, or any other boxed cake mix you like.