Mix together the cake mix, melted butter, and the egg.
Press the base into a 9×13 pan coated with cooking spray.
Blend together the cream cheese and pumpkin.
Add the eggs.
Pour in the melted butter and vanilla.
Add the cinnamon and nutmeg.
Add the box of powdered sugar. Mix until combined.
Pour the filling over the base and bake in a preheated 350 degree oven for 40 to 50 minutes.
Be careful not to overbake. You want the cake to be, well, gooey. I did overbake this a little and it was still amazing.
Top with some freshly whipped cinnamon whipped cream.