01 - Preheat the oven to 350°F. Grease a 9x13-inch baking pan thoroughly.
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 baking pan and spread into an even layer.
04 - Sprinkle the dry yellow cake mix evenly over the pumpkin layer, ensuring complete coverage without mixing or stirring.
05 - Drizzle the melted butter evenly over the surface of the cake mix, striving to moisten as much of the mix as possible. Scatter chopped pecans across the top, if using.
06 - Bake for 45 to 55 minutes, or until the topping is golden brown and the center is set. The dessert will firm up during cooling.
07 - Allow to cool for at least 30 minutes before slicing. Serve warm or chilled, optionally garnished with whipped cream or vanilla ice cream.