Preheat Oven – Preheat oven to 350°F (175°C). Grease a 9x13-inch baking dish.
Make Pumpkin Layer – In a bowl, whisk together pumpkin puree, evaporated milk, sugar, eggs, pumpkin pie spice, and cinnamon until smooth. Pour into the baking dish.
Add Cake Mix – Sprinkle the dry cake mix evenly over the pumpkin layer. Do not stir.
Drizzle Butter – Slowly pour melted butter over the cake mix, covering as much as possible.
Add Toppings (Optional) – Sprinkle chopped pecans on top for extra crunch.
Bake – Bake for 50-55 minutes or until the top is golden brown and the edges are bubbling.
Cool & Serve – Let cool for 10-15 minutes before serving. Best enjoyed with whipped cream or vanilla ice cream!