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 homogenous.
03 - Pour the pumpkin mixture into the prepared baking pan and spread it into an even layer.
04 - Evenly distribute the dry yellow cake mix over the surface of the pumpkin layer without mixing.
05 - Drizzle melted butter uniformly over the dry cake mix to ensure thorough coverage.
06 - Sprinkle chopped pecans evenly over the top, if using.
07 - Bake for 45 to 55 minutes, or until the surface is golden brown and the center is set. The structure will firm up more as it cools.
08 - Allow the dessert to cool in the pan for at least 30 minutes before serving. Serve warm or chilled, optionally with whipped cream or vanilla ice cream.