Preheat the oven to 350°F.
Add the pumpkin puree, evaporated milk, sugar, pumpkin pie spice, and eggs to a mixing bowl. Mix until smooth and well combined.
Pour the pumpkin mixture evenly into a 9 x 13-inch baking dish.
Sprinkle the dry yellow cake mix evenly over the pumpkin layer. Do not prepare the cake mix according to the package instructions and do not stir it into the pumpkin.
Sprinkle the chopped pecans evenly over the cake mix.
Distribute the butter pieces across the surface, covering as much of the cake mix as possible.
Bake for approximately 1 hour.
Remove the pumpkin crunch cake from the oven and allow it to cool completely before frosting.
Beat the softened cream cheese, powdered sugar, and whipped topping together until smooth and fluffy.
Spread the cream cheese frosting evenly over the cooled cake.
Refrigerate until ready to serve, or serve once the cake is completely cooled and frosted.