In an electric mixer or a large bowl, beat the cream cheese and butter together until smooth. Beat in the egg, then the vanilla. Slowly beat in the cake mix (it will explode everywhere if you don’t go slow). Cover and refrigerate 2 hours (or overnight) to firm up so that you can easily roll the dough into balls.
Preheat the oven to 350.
Using a tablespoon scoop or spoon, evenly scoop and roll the dough into balls. Then, roll the balls into the powdered sugar until liberally coated all over. Place onto ungreased cookie sheets, 2” apart. Bake 15 minutes then remove from the oven and allow to cool on the cookie sheet. The cookies will still be very gooey and soft. Cool completely, then sprinkle with more powdered sugar if desired.