Put the milk into a double boiler with the salt; when it is scalded add the butter and flour, which have been rubbed together. Stir for ten minutes to cook the flour and form a smooth paste; then turn it onto the yolks of the eggs, which, with the sugar added, have been beaten to a cream. Mix thoroughly, flavor, and set away to cool; rub a little butter over the top, so that no crust will form. Just before time to serve, fold into it lightly the whites of the eggs, which have been beaten to a stiff froth. Turn it into a buttered pudding-dish and bake in a moderate oven for thirty to forty minutes; or, put the mixture into buttered paper cases, filling them one half full, and bake ten to fifteen minutes. Serve with the souffle foamy sauce (page 445). This souffle may be varied by using different flavors; also by putting a layer of crushed fruit in the bottom of the dish, or by mixing a half cupful of fruit-pulp with the paste before the whites are added. In this case the whites of two more eggs will be needed to give sufficient lightness. Serve at once after it is taken from the oven.