01 - Preheat 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 the mixture is smooth and uniform.
03 - Pour the pumpkin mixture into the prepared baking pan and spread evenly.
04 - Sprinkle the dry yellow cake mix evenly over the pumpkin base, ensuring full coverage without stirring.
05 - Drizzle the melted butter evenly over the surface of the cake mix, covering as much of the surface as possible.
06 - Scatter chopped pecans over the buttered cake mix layer, if desired.
07 - Bake for 45 to 55 minutes, or until the surface is golden brown and the center is set.
08 - Allow to cool for at least 30 minutes. Serve warm or chilled, garnished with whipped cream or vanilla ice cream if desired.