Preheat over to 350. Combine cake mix, egg, and butter and mix well with an electric mixer. Pat mixture into bottom of a lightly greased 13 X 9 baking pan.
To make the filling: Beat pumpkin and cream cheese in a large bowl until smooth. Add the eggs, vanilla, and butter and beat together. Next, add the powdered sugar, cinnamon, nutmeg and mix well. Spread pumpkin mixture over cake batter and bake 40-50 minutes. Make sure not to over bake as the center should be gooey. Cut into squares and top each with toasted pecan half.