Preheat your oven to 350°F (175°C). Grease a 13×9-inch baking dish.
In a large bowl, combine the pumpkin, evaporated milk, eggs, sugar, cinnamon, and salt.
Mix until well combined. For a smoother texture, you can use an electric mixer.
Pour the pumpkin mixture into the prepared baking dish, spreading it evenly.
Sift the yellow cake mix to remove lumps, then sprinkle it evenly over the pumpkin mixture.
Sprinkle chopped pecans evenly over the cake mix layer.
Drizzle the melted butter evenly over the pecans.
Bake in the preheated oven for 50-55 minutes, or until the top is golden brown and the cake is set.
Allow the cake to cool completely. Serve chilled or warm, topped with a dollop of Cool Whip.