Preheat your oven to 350°F (175°C).
In a mixing bowl, combine the cake mix, melted butter, and 1 egg. Mix until well combined.
Press the mixture into the bottom of a greased 9x13 inch baking pan.
In another bowl, beat the softened cream cheese until smooth.
Add the remaining eggs, powdered sugar, milk, and vanilla. Mix until smooth and creamy.
Pour the cream cheese mixture over the crust in the baking pan.
Bake for 40-45 minutes, until the edges are golden and the center is slightly jiggly.
Let it cool completely in the pan.
Chill in the refrigerator for at least 2 hours before serving.
Dust with powdered sugar before slicing and serving.