Generously coat a 9-inch round baking pan with non-stick spray, and preheat oven to 350 F.

Make the top layer first by beating cream cheese until smooth. Add eggs and vanilla, and beat until light. Add confectioner’s sugar, and mix completely. Then stir in the melted butter. Set aside.

Make the base layer by combining the cake mix, egg, and butter. Mix just until combined, and press into bottom of prepared pan.

Top with cream cheese mixture, and bake for 45-55 minutes. Watch carefully. You want the center to have a little jiggle, but not too much.

Cool completely on a wire rack, and then refrigerate several hours or overnight. Cut into wedges and serve.