This Italian fresh cheese is made from the watery whey that's drained off in the production of mozzarella, provolone, and other cheeses. Ricotta cheese is sweeter and smoother than cottage cheese, and it's much richer in calcium. You can eat it straight from the tub with fresh fruit, but it's more commonly used as an ingredient in pasta dishes and desserts. Italian ricotta cheeses are made exclusively with whey, while American versions add milk as a stretcher. Low-fat versions are available, and they work quite well in cheesecakes. Use the cheese within a few days after purchasing, and throw it out if mold appears or if it tastes too acidic.