01 - Preheat the oven to 350°F. Grease a 9x13-inch baking pan and set aside.
02 - In a large mixing bowl, whisk together pumpkin puree, sweetened condensed milk, eggs, pumpkin pie spice, granulated sugar, and salt until thoroughly blended.
03 - Pour the pumpkin mixture into the prepared baking pan, spreading it evenly to the edges.
04 - Sprinkle the dry yellow cake mix evenly over the pumpkin layer without stirring or mixing.
05 - Slowly drizzle melted butter over the entire surface of the cake mix, ensuring as much coverage as possible. Evenly scatter chopped pecans on top, if desired.
06 - Bake in the preheated oven for 45 to 55 minutes, or until the top is golden brown and the center is set. The dessert will continue to firm as it cools.
07 - Allow the dessert to cool in the pan for at least 30 minutes before slicing. Serve warm or chilled, optionally garnished with whipped cream or vanilla ice cream.