Preheat oven to 350 degrees F. Grease a 9X13-inch pan with nonstick cooking spray and set aside.
In a large mixing bowl, combine pumpkin, evaporated milk, eggs, sugars, pumpkin pie spice. Pour into the prepared baking dish and spread evenly.
Sprinkle dry yellow cake mix evenly over pumpkin mixture.
Sprinkle chopped nuts over the cake mix.
Drizzle melted butter evenly over everything.
Bake at 350 degrees for 50-60 minutes or until top is golden brown. Cool completely, then cut into squares and served.
This pumpkin dump cake is delicious topped with vanilla ice cream or whipped cream!