Preheat the oven to 350 degrees.
In a large bowl, mix together your pumpkin, evaporated milk, eggs, sugar, cinnamon, pumpkin pie spice, vanilla, and salt. Stir together till smooth.
Pour mixture into a greased 9x13 pan.
Sprinkle yellow cake mix over the top of the pumpkin evenly.
Sprinkle chopped pecans over the top of the cake mix.
Cut butter very thinly and spread evenly over the top of the cake mix and pecans.
Bake for 50-60 minutes until the cake is golden brown.
Serve warm topped with vanilla ice cream.