01 - Preheat oven to 350°F. Grease a 9x13-inch baking pan.
02 - In a large mixing bowl, whisk pumpkin puree, sweetened condensed milk, eggs, pumpkin pie spice, sugar, and salt until smooth.
03 - Pour the pumpkin mixture into the prepared pan and spread evenly.
04 - Sprinkle dry yellow cake mix evenly over the pumpkin layer without mixing.
05 - Drizzle melted butter slowly over the cake mix, covering as much of the surface as possible.
06 - Scatter chopped pecans over the top if desired.
07 - Bake for 45 to 55 minutes, or until the top is golden brown and the center is set.
08 - Allow to cool for at least 30 minutes before serving. Serve warm or chilled. Garnish with whipped cream or vanilla ice cream if desired.