01 - Preheat oven to 350°F (175°C) and grease a 9x13-inch baking dish with nonstick spray or butter.
02 - In a large mixing bowl, combine pumpkin puree, evaporated milk, eggs, granulated sugar, cinnamon, nutmeg, and salt. Whisk thoroughly until smooth and homogeneous.
03 - Pour the pumpkin filling evenly into the prepared baking dish, smoothing the surface with a spatula.
04 - Evenly sprinkle the entire box of dry yellow cake mix over the pumpkin filling. Do not stir.
05 - Scatter the chopped pecans evenly across the top of the cake mix layer.
06 - Drizzle the melted butter evenly over the surface, taking care to moisten as much of the dry cake mix as possible.
07 - Place the dish on the center rack and bake for 50 to 60 minutes, or until the top is golden brown and the edges are bubbling.
08 - Remove from the oven and allow to cool for at least 30 minutes. Serve warm or chilled, optionally accompanied by whipped cream or vanilla ice cream.