This classic French onion soup builds deep flavor from slowly browned onions, savory beef broth, and a crisp baguette topping under bubbling Gruyère. The key is patience: give the onions time to soften and turn a rich amber before adding the broth. Use the button below to jump straight to the printable recipe.
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Why this French onion soup works
Yellow onions become sweet and savory when cooked slowly in butter. Dry white wine loosens the browned flavor from the pot, while thyme and bay leaf keep the broth aromatic without overpowering it. A low-sodium broth gives you room to season at the end, especially because Gruyère adds saltiness.
Ingredients and helpful swaps
Choose firm yellow onions and slice them evenly so they soften at a similar pace. Gruyère melts smoothly and has a nutty flavor; Swiss cheese is a practical substitute. If you prefer not to cook with wine, deglaze with additional broth and a teaspoon of cider vinegar. Use a sturdy baguette that can hold its shape under the cheese.
How to make it
Start the onions over medium heat, then reduce the burner if they color too quickly. Stir every few minutes and scrape the bottom of the pot; the gradual 45-to-55-minute cook is what develops the soup’s signature flavor. Once the onions are deep golden, add garlic briefly, deglaze with wine, and simmer the broth with thyme and bay for 25 minutes.
Toast the baguette separately so it stays crisp. Ladle the soup into oven-safe bowls on a rimmed sheet pan, top with toast and Gruyère, and broil just until the cheese bubbles and browns in spots. Stay beside the oven: broilers can go from melted to scorched quickly. If you do not own broiler-safe bowls, melt the cheese on the toast on a baking sheet and float each cheesy toast on the soup.
Make-ahead, storage, and serving
The onion broth can be made up to three days ahead and refrigerated in a covered container; add the bread and cheese only when serving. Cool leftovers promptly, refrigerate within two hours, and reheat the broth until steaming. For practical storage timelines, see the FoodSafety.gov cold-storage chart. The finished bowls are best eaten immediately because the toast softens.
Serve this soup as a cozy starter or pair a bowl with a simple green salad. For another hearty dinner idea, try our homemade cheeseburger recipe.
Estimated nutrition per serving
Approximate values for one of six servings with baguette and Gruyère. Actual values vary with the bread, broth, and cheese brands.
| Nutrient | Amount |
|---|---|
| Calories | 490 kcal |
| Carbohydrates | 38 g |
| Protein | 22 g |
| Total fat | 28 g |
| Saturated fat | 15 g |
| Fiber | 4 g |
| Total sugars | 13 g |
| Sodium | 1,250 mg |
Nutrition is an estimate, not a laboratory analysis.
Recipe notes
- Do not rush the onions; pale onions make a lighter, less complex broth.
- Broil the cheese topping just before serving for the best contrast of crisp bread and melted cheese.
- For a vegetarian version, use vegetable broth and omit Worcestershire or choose a vegetarian version.
Classic French Onion Soup
Ingredients
Method
- Melt the butter in a large heavy pot over medium heat. Add the onions, salt, and optional sugar. Cook, stirring every few minutes, for 45 to 55 minutes until deeply golden and very soft; lower the heat if the edges brown too quickly.
- Stir in the garlic and cook for 30 seconds. Pour in the wine and scrape up the browned bits. Simmer until nearly evaporated, about 3 minutes.
- Add the beef broth, Worcestershire, thyme, bay leaf, and pepper. Bring to a gentle boil, then reduce heat and simmer uncovered for 25 minutes. Remove the thyme stems and bay leaf; taste and adjust seasoning.
- Heat the broiler. Arrange baguette rounds on a baking sheet and toast for 1 to 2 minutes per side until crisp.
- Ladle soup into broiler-safe bowls set on a rimmed baking sheet. Add one or two toast rounds and a generous layer of Gruyere to each bowl.
- Broil 1 to 3 minutes, watching closely, until the cheese is melted, bubbling, and spotted golden. Serve hot; handle the bowls carefully.
