Combine pumpkin puree, evaporated milk, sugar, eggs and spices in a large bowl and whisk to combine.
Grease a 9"x13" baking dish with a little butter.
Pour in pumpkin mixture into buttered baking dish.
Sprinkle the yellow cake mix over the pumpkin mixture, trying to get it as evenly spread as possible.
Pour the melted butter over the cake mix, covering all the cake mix as much as you can.
Top with chopped pecans spread out over the entire cake
Bake 50 minutes to 55 minutes, or until the cake is firm, and cooked through. The cake should be a nice browned color and but the middle is still ooey and gooey.
Remove from oven, and serve hot or cold with ice cream or cream.
Optional - add Pumpkin Whipped Cream Mix 1 cup of ready made or homemade whipped cream with 1 tablespoon of pumpkin spice and mix well.
Refrigerate and serve with on top of the pumpkin cake.
When you sprinkle the boxed cake mix over the pumpkin puree mixture, make sure it's as even as possible so that it can expand evenly over the cake.IMPORTANT TIP: Use unsalted butter to finish off the cake, and make sure all the boxed cake mix is covered in butter to ensure even baking. You may want to use a pastry brush to ensure the butter is spread evenly. If it is not completely covered, you may need to melt a little more butter.Make this an over the top Fall dessert by topping with Pumpkin Spice Whipped Cream. You can spoon it on top or get fancy and use a piping bag.