Almost all modern cheesecakes in the United States and Canada use cream cheese; in Italy, cheesecakes use ricotta; Germany, the Netherlands and Poland use quark. Cheesecakes are most easily baked in a leak-proof springform pan, often paired with a water bath to more evenly distribute the heat.[9] Because of the high density of most cheesecakes, they continue baking for some time after removal from an oven. Whether baked cheesecake should be classified as a cake, a custard, a torte, or something else is a matter of debate. The early Greeks considered it a cake. Some modern authors point to the presence of many eggs, the sole source of leavening, as proof that it is a torte. Still others claim that the separate crust, the soft filling, and the absence of flour prove that it is a custard pie.Ricotta (Italian pronunciation: [ri?k?tta]) is an Italian whey cheese made from sheep (or cow, goat, or buffalo) milk whey left over from the production of cheese. Like other whey cheeses, it is made by coagulating the proteins that remain after the casein has been used to make cheese, notably albumin and globulin. Thus, ricotta can be eaten by persons with casein intolerance. Ricotta (literally meaning "recooked") uses whey, the liquid that remains after straining curds when making cheese. Most of the milk protein (especially casein) is removed when cheese is made, but some protein remains in the whey, mostly albumin. This remaining protein can be harvested if the whey is first allowed to become more acidic by additional fermentation (by letting it sit for 12Ц24 hours at room temperature). Then the ac dified whey is heated to near boiling. The combination of low pH and high temperature denatures the protein and causes it to precipitate out, forming a fine curd. Once cooled, the curd is separated by passing through a fine cloth. Ricotta curds are creamy white in appearance, slightly sweet in taste, and contain around 13% fat. In this form, it is somewhat similar in texture to some cottage cheese variants, though considerably lighter. It is highly perishable. Ricotta comes in other forms as well, see variants below. Custard is a variety of culinary preparations based on a cooked mixture of milk or cream and egg yolk. Depending on how much egg or thickener is used, custard may vary in consistency from a thin pouring sauce (creme anglaise), to a thick pastry cream used to fill eclairs. Most common custards are used as desserts or dessert sauces and typically include sugar and vanilla. Custard bases may also be used for quiches and other savory foods. Sometimes flour, corn starch, or gelatin is added as in pastry cream or creme patissiere. Custard is usually cooked in a double boiler (bain-marie), or heated very gently in a saucepan on a stove, though custard can also be steamed, baked in the oven with or without a water bath, or even cooked in a pressure cooker. Custard preparation is a delicate operation, because a temperature increase of 5Ц10 ∞F (3-6 ∞C) leads to overcooking and curdling. Generally, a fully cooked custard should not exceed 80 ∞C; it begins setting at 70 ∞C.[1] A water bath slows heat transfer and makes it easier to remove the custard from the oven before it curdles.[2]