Gruyère is the classic cheese for French onion soup, with Comté as an equally traditional French alternative.

Best traditional choices

  • Gruyère : Semi-hard Swiss cheese that grates easily, melts smoothly, and adds a nutty, slightly salty flavor without overpowering the onions.
  • Comté : French Alpine cheese very similar to Gruyère, often favored by French cooks for onion soup and considered a “definitive” choice in French discussions.

Other good melting cheeses

Many modern recipes use a blend for extra melt and cheese pull.

  • Provolone (for stretch and mild richness).
  • Mozzarella or Fontina (great melt, mild flavor; avoid fresh mozzarella as it can get watery).
  • Emmental/“Swiss,” Beaufort, Appenzeller and similar Alpine cow’s milk cheeses.

Cheeses to be careful with

  • Parmesan/Parmigiano-Reggiano is sometimes added in small amounts to blends for extra sharpness but is not traditionally used alone on top, and some French commenters suggest avoiding it as a main topping.

Simple rule of thumb

For a classic, restaurant-style bowl:

  • Use mostly Gruyère or Comté , grated.
  • Optionally mix in a little provolone or mozzarella for extra stringiness on top of the toasted bread.

Information gathered from public forums or data available on the internet and portrayed here.