The Gruyère Swap You Should Try When Making French Onion Soup
Made with just beef broth, onions, bread, and cheese, a simple French onion soup recipe is always a comforting treat. Many chefs use their own twists and tricks to elevate the dish, such as the beef consommé in Alton Brown's swap for richer French onion soup, while Jamie Oliver puts an English spin on the soup with leeks, Worcestershire sauce, and cheddar. And while Gruyère is the cheese traditionally used to adorn the toasty croutons on top, it's easy to add extra flavor and texture by trying an alternative cheese.
The cheese in French onion soup serves two purposes. It boosts the taste by adding rich, umami savoriness to pair with the robust beef and sweet onion flavors, and it also must melt well, so you get that gorgeously gooey texture that makes every mouthful a joy. Swiss or raclette cheese both make excellent alternatives to Gruyère, as they tick all these boxes in terms of taste and texture. If you really want to go all-out, you could try a blend of both cheeses in your bowl. Incorporating a mixture of a stronger-tasting cheese along with a good melter makes for even cheesier croutons that deserve to be the star of the dish.
Swiss or raclette cheese add rich savory flavor
Creamy and nutty in flavor, Gruyère is a cheese made with cow's milk that comes from Gruyères, a French-speaking town in Switzerland. It makes sense to replace it with another type of Alpine-style Swiss cheese in French onion soup. Emmentaler, a Swiss cow's milk cheese also known as Emmental, is a good bet, since it has a great melting ability and is often used in fondue. It also adds a lovely buttery flavor. Emmentaler is the model for what Americans know as holey "Swiss" cheese.
Raclette is another cheese which melts even better. It's often served in the dish of the same name, in which the hot, runny, gooey cheese is draped over baby potatoes, cornichons, and cured meats. This Alpine cow's milk cheese is made in both Switzerland and France, with the Swiss variety having a lightly pungent flavor that confidently stands up to a rich, beefy broth.
American Swiss cheese also makes a good switch for the Gruyère. As the name suggests, it's made in the States, but in the Swiss style. It's a much more wallet-friendly alternative to both authentic Emmentaler and raclette, so it's great if you're making a large batch of soup for a dinner party. Generic Swiss is also widely available in grocery stores, and has a mildly nutty taste that suits those French onion flavors.
Add provolone or mozzarella for the ultimate cheese pull
Since the cheese on French onion soup has to melt beautifully, you might think that different types of mozzarella or provolone would be a good bet. However, when used alone, these cheeses can sometimes add an oily texture to the soup. Plus, while mozzarella is gooey when just-melted, it also becomes firm or even rubbery when it cools – not an ideal texture for serving in soup.
To get the best out of these cheeses, it's worth considering a blend. Try mixing provolone or mozzarella with shredded Gruyère or one of the suggested alternatives for a full-flavored result, along with an impressive cheese pull. If you want to add even more of a salty, savory flavor, consider adding a little punchy Parmesan to the mix. Mixing mozz with another cheese will slow down that congealing effect.
To get the best results with your cheesy croutons, crisp up one side of the bread first under the broiler. Thick slices of baguette work well, as they also soak up the broth nicely. Ladle the soup into oven-proof bowls, lay the crispy bread on top, and sprinkle the cheese generously over the surface. Broil until the cheese is bubbling, and keep a close eye on it so that it doesn't go from golden brown to burned. Garnish with fresh thyme or parsley, and you have one fine serving of soup.