01 - Preheat oven to 350°F. Lightly grease a 9x13-inch baking pan with nonstick spray or butter.
02 - In a large mixing bowl, whisk pumpkin puree, sweetened condensed milk, eggs, pumpkin pie spice, granulated sugar, and salt until smooth and well blended.
03 - Pour the pumpkin mixture into the prepared baking pan and spread evenly with a spatula.
04 - Sprinkle the dry yellow cake mix evenly over the pumpkin layer without mixing. Ensure full, even coverage.
05 - Drizzle melted butter evenly over the surface of the cake mix. Top with chopped pecans if using.
06 - Place the pan in the oven and bake for 45 to 55 minutes, or until the top is golden brown and the center is just set.
07 - Remove from oven and allow to cool for at least 30 minutes before serving. Serve warm or chilled with optional whipped cream or vanilla ice cream.