Spray 9x13 baking dish with nonstick cooking spray.
In large mixing bowl, combine Pumpkin, Brown Sugar, White Sugar, and Pumpkin Pie Spice and stir with a large spoon until well combined.
Then add in the eggs, and continue stirring until all is combined.
Now slowly drizzle in Evaporated Milk, while continuing to stir.
Evenly spread out Pumpkin Pie Mixture in baking dish.
In medium mixing bowl, combine dry Spice Cake Mix and 3/4 cup melted Butter, and stir until crumbly. {break up any large chunks into small crumbles with spoon or your fingers}
Sprinkle crumble mixture evenly over pumpkin layer in baking dish.
Optional: Then evenly sprinkle pecan pieces on top of the crumble mixture.
Drizzle the top evenly with the remaining 1/4 cup of melted Butter.
Bake for 50 - 60 minutes, or until done.
Allow cake to cool for at least 1 hour prior to serving.
Serve warm with a scoop of vanilla ice cream... OR transfer cooled cake to refrigerator for a few hours, and serve chilled with whip cream on top!
Storage Tip: Leftovers can be stored in the pan covered with plastic wrap or aluminum foil. Store leftovers in the refrigerator for 3 - 4 days.
Notes
*Note: If you can't find a spice cake mix, try this as a substitute: Use a Yellow Cake Mix, and whisk in the following: 1 3/4 tsp. Ground Cinnamon, 1/2 tsp. Ground Ginger, 1/4 tsp Ground Nutmeg, 1/4 tsp. Ground Cloves.