Gruyere cheese is the traditional choice for French onion soup, but other cheeses can be used as well. Some recipes call for a mix of cheeses, such as provolone and gruyere, or Swiss, mozzarella, and parmesan. The cheese should be finely grated, melt easily, and not overpower the other flavors of the soup. It should also have a touch of pull and not be oily. Here are some of the best cheeses for French onion soup:

• Gruyere: a semi-hard cheese that has a slightly nutty, salty flavor and a creamy texture. It is slow melting and adds a creamy flavor to the soup.

• Provolone: mild but rich with the best cheese pull-ness.

• Swiss: adds a nutty counterpoint to the onions and a rounded earthy note.

• Fontina: another mild white cheese that melts well.

• Mozzarella: avoid using fresh mozzarella as it will be watery when it melts.

• Parmesan: adds a salty, nutty flavor to the soup.

• Monterey Jack: a good general melty cheese that’s mild.

To serve, place two or three slices of baguette and a generous helping of shredded cheese over each bowl of soup, then pop the French onion soup under the broiler to toast the baguette and melt the cheese.