The crossword solution for the term 'Layer on Many Pies' is Mozzarella. Mozzarella is a type of cheese that is commonly used as a topping on pizzas. It is a soft, white cheese that is made from cow's milk and has a mild flavor. It is often used in Italian dishes such as lasagna and calzones. Mozzarella is also a popular topping for many other types of pies, such as quiche and shepherd's pie.