01 - Preheat the oven to 350°F. Grease a 9x13-inch baking pan thoroughly.
02 - In a large mixing bowl, combine pumpkin puree, sweetened condensed milk, eggs, pumpkin pie spice, granulated sugar, and salt. Whisk until the mixture is smooth and fully blended.
03 - Pour the pumpkin mixture into the greased baking pan and spread it into an even layer.
04 - Evenly sprinkle the dry yellow cake mix over the pumpkin layer without mixing.
05 - Drizzle the melted unsalted butter across the entire surface, covering as much of the top as possible.
06 - Scatter chopped pecans evenly over the buttery cake topping, if desired.
07 - Bake for 45 to 55 minutes, or until the top is golden brown and the center appears set. The dessert will continue to solidify as it cools.
08 - Allow to cool in the pan for at least 30 minutes before serving. Enjoy warm or chilled, optionally garnished with whipped cream or vanilla ice cream.