Preheat oven to 350°F (175°C) and grease a 9x13-inch baking dish.

In a large bowl, whisk together pumpkin puree, evaporated milk, granulated sugar, brown sugar, eggs, pumpkin pie spice, and salt until smooth.

Pour the pumpkin mixture into the prepared baking dish and spread evenly.

Sprinkle the entire box of yellow cake mix evenly over the pumpkin layer—do not stir.

Slowly pour melted butter over the cake mix, covering as much surface area as possible.

Bake for 50–60 minutes or until the top is golden brown and the filling is set.

Let cool for at least 15 minutes before serving. Serve warm, chilled, or at room temperature.