Preheat oven to 350°F. Quarter the pumpkin rolls. Toss the chunks of rolls into the sugar and pumpkin pie spice mixture and place into a greased skillet. Brush with melted butter and pop into the oven. Bake for 25-30 minutes. When finished baking, drizzle the frosting (included with the pumpkin rolls) on top and sprinkle with chopped walnuts. Enjoy!