01 - Preheat oven to 350°F. Grease a 9x13-inch baking pan.
02 - In a large mixing bowl, whisk together pure pumpkin puree, sweetened condensed milk, eggs, pumpkin pie spice, granulated sugar, and salt until smooth.
03 - Pour the pumpkin mixture into the prepared baking pan and spread evenly.
04 - Sprinkle yellow cake mix evenly over the pumpkin filling; do not stir.
05 - Drizzle melted butter evenly over the cake mix layer, ensuring coverage across the surface.
06 - Scatter chopped pecans over the surface if desired.
07 - Bake for 45 to 55 minutes, until the top is golden brown and the center is set.
08 - Allow to cool in pan for at least 30 minutes before serving. Serve warm or chilled, optionally with whipped cream or vanilla ice cream.