Macaroni with Tomatoes

Fry half an onion slightly in butter, and as soon as it is coloured add a puree of two big cooked tomatoes. Then boil quarter of a pound of macaroni separately, drain it and put it in a deep fireproof dish, add the tomato puree and three tablespoonsful of grated Parmesan and Cheddar mixed, and cook gently for a quarter of an hour before serving. This dish may be made with vermicelli, spaghetti, or any other Italian pasta.