This classic French onion soup turns a generous pile of yellow onions into a deeply savory broth crowned with crisp garlic toast and bubbling Gruyère.
Slow caramelization creates the soup's signature sweetness and color, while dry white wine keeps the rich beef broth balanced.
Prep: 25 min · Cook: 1 hr 50 min · Total: 2 hr 15 min
Cuisine: French · Course: Soup
French Onion Soup Recipe Card
Ingredients
Instructions
- Melt the butter with 1 tablespoon olive oil in a large Dutch oven over medium heat. Add the onions and cook, stirring occasionally, for 4–5 minutes. Reduce the heat to low, cover, and cook for 15 minutes.
- Uncover the onions. Add the sugar and 1/2 teaspoon salt, then cook, stirring occasionally, for about 25 minutes, until deeply caramelized. Stir in the flour and cook for 2–3 minutes.
- Bring the beef stock and wine to a boil in a separate saucepan. Slowly pour the hot liquid into the onions while stirring. Add 1 teaspoon black pepper, reduce the heat to medium, partially cover, and simmer for about 45 minutes.
- Preheat the broiler. Arrange the bread on a baking sheet, drizzle with the remaining olive oil, and broil for 3–4 minutes per side until golden. Rub the toast with the cut garlic.
- Heat the oven to 400°F. Divide the soup among 6–8 ovenproof bowls, top each with two toasts and Gruyère, and bake for about 15 minutes, until the cheese is melted and golden.
Tips for the Best French Onion Soup
- Slice the onions evenly so they caramelize at the same rate.
- Keep the heat low after the first few minutes; slow cooking develops sweetness without scorching.
- Use sturdy, dry bread so the toast holds its shape under the broth and cheese.
- Set the ovenproof bowls on a rimmed sheet pan before filling them for easier handling.
Substitutions and Variations
Comté, Emmental, or Swiss cheese can replace the Gruyère. For a lighter broth, use half beef stock and half chicken stock. If avoiding wine, replace it with additional stock and a teaspoon of sherry vinegar.
Storage and Reheating
Refrigerate the soup without the bread and cheese for up to 4 days, or freeze for up to 3 months. Reheat the broth on the stovetop, then assemble fresh toasts and bake just before serving.
Frequently Asked Questions
How dark should the onions be?
They should be a deep golden brown, soft, and jammy, but not blackened. This usually takes about 40–45 minutes.
Do I need ovenproof bowls?
For the traditional baked topping, yes. Otherwise, broil cheese-topped toasts on a sheet pan and place one over each serving.
Can I make the soup ahead?
Yes. The onion broth often tastes even better the next day. Add the bread and cheese only when ready to serve.
Prepared with AI assistance from a cookbook reference photo. Ingredient amounts and directions were normalized and rewritten into an original recipe. Review before cooking.
Featured image: AI-generated food photography.