Preheat your oven to 350°F. Line a baking sheet with parchment paper for easy cleanup.

In a large mixing bowl, beat the softened butter and cream cheese together until the mixture is smooth and creamy. Add the egg and vanilla extract, mixing until well combined. Gradually add the yellow cake mix, stirring until the dough comes together.

Cover the dough and refrigerate it for at least 30 minutes to make it easier to handle.

Once chilled, scoop out tablespoon-sized portions of the dough and roll each into a ball. Roll the dough balls generously in powdered sugar until fully coated.

Place the coated dough balls on the prepared baking sheet, leaving about 2 inches of space between them. Bake for 10–12 minutes, or until the cookies are set with slightly cracked tops but still soft in the center.

Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.