Preheat oven to 350°F and grease a 9x13-inch baking dish.

Mix cake mix, melted butter, and one egg until a thick dough forms.

Press dough evenly into the prepared baking dish.

Beat cream cheese until smooth, then add eggs and vanilla.

Gradually mix in powdered sugar until silky.

Spread topping over crust and bake until lightly golden with a jiggly center.

Cool completely before slicing into bars.