Preheat oven and prepare pan: Preheat oven to 350 degrees F. Grease a 9x13’’ baking pan with nonstick cooking spray and line the pan with a piece of parchment paper. Make sure the edges of the paper hang over the sides of the pan.
Prepare the pumpkin mixture: In a large bowl, mix together the pumpkin, evaporated milk, eggs, both sugars, pumpkin pie spice and salt. Whisk until well combined and smooth. Pour pumpkin mixture into prepared pan.
Add cake mix layer: Sprinkle the cake mix evenly all over the pumpkin mixture.
Add nuts: Sprinkle the nuts evenly all over the cake mix.
Add melted butter: Pour the melted butter evenly all over the top of the cake.
Add cinnamon sugar: Sprinkle the top of the cake evenly with cinnamon sugar.
Bake: Bake the cake for 50-60 minutes or until the edges are golden brown and the center is set. A toothpick inserted into the center of the cake should come out clean. (NOTE: If the pecans start to turn too brown before the cake is done baking, loosely tent the top with foil during the last 5-15 minutes of baking.) Remove the cake from oven and place pan on a wire cooling rack. Let the cake cool for at least 30 minutes in the pan before removing if you want a sliceable cake.
While the cake is cooling, make the frosting: In a large bowl with a handheld mixer or in the bowl of a stand mixer with the paddle attachment, beat the cream cheese and butter on medium speed until smooth and combined, about 3-5 minutes. Turn the mixer to low and gradually add the sugar, 1 cup at a time. Mix on low until incorporated. Add in the syrup and season with a pinch of salt. Mix on low until incorporated. Turn the mixer to medium high and beat until frosting is light and fluffy.
Allow the cake to cool: After the cake has cooled, invert the cake onto a tray or large serving plate. Allow the cake to cool completely.
Frost the cake (optional): Spread the frosting all over the cake, slice and enjoy!!
Nutritional Information based upon 12 servings and does not include frosting.