Preheat oven to 350 degrees.
In a large bowl beat together until combined pumpkin, milk, eggs, sugars, vanilla, pumpkin pie spice and salt.
Pour mixture into greased 9x13 pan.
Evenly sprinkle the dry cake mix over pumpkin mixture, layer nuts and place sliced butter over the top.
Bake for 50 minutes until cake is set.
Let cake cool then top with whipped topping and enjoy!