Cheese slices will stand in for shredded cheese in any melting application. Reduced fat cheeses do not have the same structure as regular cheeses and they become tough and rubbery with prolonged heating, according to the cheese company Sargento, so avoid using low fat cheese slices for melting. The choice of your cheese, both in its fat content and variety, and the method you use for melting it will determine whether you end up with a smooth and creamy melted cheese or a rubbery mess.
Choose a variety of cheese for better, smoother melting. Robert Wolke writing for Fine Cooking suggests the following melting cheeses: cheddar, Asiago, Gruyere, Fontina, Gouda, Monterey Jack, Emmentaler (or Emmental), Havarti and Muenster. Look for these cheeses sliced in the supermarket dairy case or ask for slices from your local deli or cheese shop.
Slice your own cheese if you cannot find pre-sliced cheese. Pull a cheese planer over the surface of a block of cheese to shave off the thinnest slice possible for optimal melting.
Set the cheese slices out on the counter for at least 30 minutes to come to room temperature before melting. This will avoid wide, rapid swings in temperature and help the cheese to melt faster.
Tear the cheese slices into smaller shreds if you're adding the slices to a sauce or using them as a topping for a casserole, sandwich or pizza.
Add the ripped cheese as a topping to a baked dish during the last five to ten minutes of cooking and remove the dish from the oven as soon as the cheese has melted.