Gratin, from the French gratter, to scrape or grate, defines a multitude of dishes whose sole purpose is to extend and glorify one basic, usually vegetable, ingredient. Chic thirties cooks, like Mrs Leyel, suggest serving a gratin of spinach or cauliflower, topped with cream, grated cheese and breadcrumbs, as a ‘light luncheon’ dish. At the other extreme a pain or loaf of lightly pre-cooked vegetable (carrot, cabbage, endive) bound with a soufflé mixture (whit