Preheat oven to 400. Peel and slice onions. Peel and slice Potatoes. Cover with hot water and add 2 tsp salt. Bring to boil and cook 5 minutes. Drain and put in a greased casserole. Mix marg and flour in microwave safe glass measuring cup. Microwave 1 minute. Add Milk slowly whisking to keep lumps from forming. Add 1 ts salt, pepper and paprika. Microwave stirring occasionally til cooked. Makes fairly loose sauce. Pour over potato/onion mixture in casserole and bake for 35 minutes.