Preheat oven to 350℉, Spray or grease 9x13” pan
Reserve 1 cup cake mix, In a large bowl, combine the remaining dry cake mix with 1 egg and ½ cup melted butter. Mix well, then pat into bottom of prepared pan.
In a large bowl, mix together the pumpkin, 3 eggs, ½ cup white sugar, brown sugar, and cinnamon. Pour over crust.
In a small bowl, combine reserved 1 cup cake mix, ½ cup white sugar, and 3 T. softened butter. Crumble over pumpkin filling. Sprinkle nuts evenly over the top if desired.
Bake in preheated oven for 40-45 minutes.