Allow about one sausage per person. Then layer the onions and sausage on top of the potato. Add a layer of tomato, cover with cheese sauce, and bake in a hot oven till the cheese sauce looks golden brown and bubbly. Grate two roast or baked potatoes, or measure out about a cup and a half of mash. Stir in the mashed potato.
Medium heat is best.
This quantity will make about eight, or two each. Once the little cakes bubble, flip them over and cook for about the same amount of time so that both sides are golden brown. You can serve with bacon, or eggs, or sausages or tomatoes or sour cream, or just eat them on their own. You can use exactly the same mixture to make potato waffles. Just ladle into a waffle iron and cook until done.