01 - Preheat oven to 350°F. Generously grease a 9x13-inch baking pan to prevent sticking.
02 - In a large mixing bowl, whisk pumpkin puree, sweetened condensed milk, eggs, pumpkin pie spice, granulated sugar, and salt until smooth and homogeneous.
03 - Pour the pumpkin mixture into the prepared pan and spread evenly using a spatula.
04 - Evenly distribute the dry yellow cake mix over the pumpkin layer, ensuring full coverage without mixing.
05 - Drizzle melted butter evenly over the cake mix, covering as much surface as possible. Sprinkle chopped pecans over the top if desired.
06 - Bake for 45 to 55 minutes, or until the surface is golden brown and the center is set. The dessert will firm as it cools.
07 - Let cool for at least 30 minutes before slicing. Serve warm or chilled, optionally garnished with whipped cream or vanilla ice cream.