01 - Preheat oven to 350°F. Grease a 9x13-inch baking pan to prevent sticking.
02 - In a large mixing bowl, whisk together pumpkin puree, sweetened condensed milk, eggs, pumpkin pie spice, granulated sugar, and salt until smooth and homogeneous.
03 - Transfer the blended pumpkin mixture into the prepared baking pan, smoothing the surface evenly with a spatula.
04 - Sprinkle the dry yellow cake mix uniformly over the pumpkin layer without mixing.
05 - Drizzle melted butter evenly across the entire surface to moisten the cake mix as thoroughly as possible.
06 - Evenly distribute chopped pecans over the top if desired for added crunch and flavor.
07 - Bake for 45 to 55 minutes until the top is golden brown and the center is set. The dessert will firm as it cools.
08 - Allow to cool for at least 30 minutes before cutting. Serve warm or chilled, optionally garnished with whipped cream or vanilla ice cream.