Preheat your oven to 350°F (175°C) and grease a 9x13 inch baking pan.
In a bowl, mix the cake mix, melted butter, and 1 egg until combined.
Press the mixture into the bottom of the prepared pan.
In another bowl, beat the cream cheese until smooth.
Add 2 eggs, powdered sugar, and vanilla extract to the cream cheese and mix well.
Pour the cream cheese mixture over the cake layer.
Bake for 40 minutes, until the center is slightly jiggly.
Let it cool before cutting into squares.
Serve warm or at room temperature.