Here is your basic simple leftover casserole that although ,it uses the same ingredients, tastes very different. Quick do ahead. Plan for this casserole the next time you do mashed potatoes, gravy and roast
Fry the onions in a hot dry skillet, sprinkle with the sugar or sweetener and cook until the onions start to brown. Add margarine and cook until they are tender, stir occasionally.
Remove from heat.
Spray a shallow baking dish with veggie oil and spread half the mashed potatoes on the bottom, then the meat, onions, peas and gravy. Cover with the remaining mashed potatoes, sprinkle with the Parmesan. Bake in a 375 F oven for 35 minutes. Sprinkle with paprika and serve.