Place the cake mix, eggs, and thawed whipped topping in a large bowl. Blend for 1-2 minutes with an electric mixer set on medium speed until well blended and all dry ingredients are moistened (dough will be stiff). Refrigerate dough, covered, for 30 minutes.
Preheat oven to 350°F. Position oven rack in middle of oven. Set aside ungreased cookie sheets. Place sifted powdered sugar in a small, shallow dish.
Shape dough into 1-inch balls. Roll cookies in powdered sugar to coat. Place 2 inches apart on ungreased cookie sheet.
Bake for 10-12 minutes or until cookies are puffed in appearance and firm at edges (centers will still be slightly soft). Let cookies rest on cookie sheets for 2 minutes (cookies will fall, giving them a cracked appearance). Transfer cookies to wire rack with metal spatula and cool completely.