01 - Preheat oven to 350°F. Grease a 9x13-inch baking pan.
02 - In a large mixing bowl, whisk together 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 use a spatula to spread evenly.
04 - Distribute dry yellow cake mix evenly over the pumpkin mixture without stirring.
05 - Drizzle melted butter evenly over the cake mix, ensuring maximum coverage.
06 - Sprinkle chopped pecans over the surface if using.
07 - Bake in the preheated oven for 45 to 55 minutes, or until the top is golden brown and the center is just set.
08 - Allow to cool for at least 30 minutes before slicing. Serve warm or chilled. Optionally garnish with whipped cream or vanilla ice cream.