Preheat your oven to 350 and prepare your baking dish by buttering or spraying with cooking spray
In a medium bowl, combine the yellow cake mix, one egg, and melted butter and press into the bottom of the prepared baking pan
In a large bowl or the bowl of your electric mixer, mix the cream cheese on medium speed until light and fluffy. Add in the remaining eggs, vanilla and powdered sugar and spread the cream cheese mixture in the baking pan with a spatula. Bake 30-40 minutes, until nearly firm (the cake should still shake in the middle when jiggled). Remove from oven and cool.
Once cooled, dust with powdered sugar and cut into squares.
Notes
You can make this cake ahead of time and chill in the fridge for up to one day.