Preheat oven 350 degrees.
In a large bowl combine the pumpkin puree, evaporated milk, eggs,
sugar, and pumpkin pie spice. Mix well and pour into a 9 x 13 pan.
Add the salt to the cake mix and sprinkle it on top of the pumpkin mixture.
Melt the butter and pour over top of the cake mix.
Bake for 55 minutes. Remove from oven and cool on a wire rack. Refrigerate for 2-3 hours or until ready to serve.