Preheat the oven to 350℉. Spray a 9x13-inch baking dish with nonstick spray.
First Layer
In a large bowl, mix together cake mix, butter, egg, and water until well combined. Spread evenly in the bottom of the baking dish.
Second Layer
In a medium bowl, mix together cream cheese, eggs, and vanilla with an electric mixer on medium speed. Gradually mix in powdered sugar until smooth and creamy. Spread over the top of the cake mix layer.
Bake 30 to 40 minutes, or until edges are golden brown. Let cool completely. Sprinkle with powdered sugar before serving.
Notes
Variation: Fold in coconut and pecans to the cream cheese mixture before adding to the top. Make ahead: This cake actually tastes better the longer it sits, and is perfect for baking a day in advance. Recipe slightly adapted from Allrecipes