1In a bowl, mix pumpkin puree, three eggs, evaporated milk, 3/4 cup sugar, 1 teaspoon pumpkin pie spice, 1 teaspoon vanilla, and 1 teaspoon of sea salt.
2Pour the mixture into a generously buttered 13x9 inch pan.
3Layer a box of yellow cake mix (or about three cups of homemade cake mix) over the pumpkin mixture.
4Sprinkle chopped walnuts over the cake mix.
5Layer the remaining cake mix over the walnuts.
6Pour the melted butter over the top layer.
7Bake at 350 degrees Fahrenheit for 55 minutes.
8Let it cool for an hour then flip it out of the pan.
9Top with whipped cream and sprinkle with cinnamon.