Preheat your oven to 350℉. Spray a 9x13 inch baking pan with nonstick spray.
Prepare the crust: In a large bowl, use an electric mixer to combine the cake mix, egg and butter. Pat the mixture into the bottom of your prepared pan.
Prepare the filling: In a large bowl, use an electric mixer to combine the cream cheese and pumpkin until smooth. Add the eggs, vanilla and butter- beat well. Mix in the powdered sugar, cinnamon and nutmeg until well-combined.
Spread the filling over the cake batter and bake 40 to 50 minutes. Don't over bake; you want the center to be a little gooey!