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 thoroughly blended.
03 - Pour the pumpkin mixture evenly into the prepared pan.
04 - Sprinkle the dry yellow cake mix uniformly over the pumpkin layer without stirring.
05 - Drizzle the melted butter evenly over the surface, aiming to cover as much of the cake mix as possible. Scatter chopped pecans over the top, if using.
06 - Bake in the center of the oven for 45 to 55 minutes until the top is golden brown and the center is set.
07 - Allow 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.