French Onion Soup

Ingredients

• 57 g (4 tablespoons)unsalted butter
• 5 largeyellow onions, thinly sliced
• 1 teaspoonsalt
• 16 g (2 tablespoons)plain flour
• 120 ml (1/2 cup)dry white wine
• 1.4 litres (6 cups)beef broth
• 1bay leaf
• 1 teaspoondried thyme
• 1 baguette, sliced into 2.5 cm (1-inch) thick piecesbaguette
• 225 g (8 ounces)Gruyère cheese, shredded

Instructions

1. 1

   Caramelise onions

   Melt the butter in a large pot over medium heat. Add the sliced onions and salt, then cook for 30–40 minutes, stirring occasionally, until the onions are caramelised.

2. 2

   Cook the flour

   Sprinkle the flour over the caramelised onions, stir it in and cook for 2 minutes.

3. 3

   Deglaze the pot

   Pour in the white wine and scrape up the browned bits from the bottom of the pot. Let the wine reduce for about 5 minutes.

4. 4

   Simmer the soup

   Add the beef broth, bay leaf and thyme. Bring the soup to a simmer and cook uncovered for 30 minutes.

5. 5

   Toast the bread

   Preheat the oven to 200°C (400°F). Arrange the baguette slices on a baking sheet and toast for about 5–7 minutes, until golden.

6. 6

   Assemble the bowls

   Put toasted baguette slices on top of the soup in oven-safe bowls and scatter over the shredded Gruyère.

7. 7

   Melt the cheese

   Place the bowls under the grill until the cheese is melted and bubbling, about 2–3 minutes. Serve hot.

What is French onion soup?

French onion soup is a classic French dish of onions cooked until deeply golden, served in a savoury broth with bread and melted cheese. This version builds its flavour from caramelised onions, beef broth, white wine and thyme.

The slow cooking is what makes this recipe work: the onions become sweet and tender before the broth is added, while toasted baguette and Gruyère make a crisp-edged, gooey topping.

Nutrition and macros by portion

The nutrition label shows one serving as written: 307 calories, 10g protein, 40g carbs, 11g fat.

The onions and baguette provide most of the carbohydrates, while butter and Gruyère contribute much of the fat; the beef broth and cheese supply protein. For a more balanced plate, serve a bowl with a crisp green salad or other vegetables.

Why the onions need time

Even slices: Cut the onions as evenly as you can so they soften at a similar pace.

Steady heat: Cook them over medium heat, stirring now and then for 30–40 minutes. They should become soft and richly golden rather than simply browned in patches.

Building the broth

Flour: Stir it through the caramelised onions and cook for 2 minutes to incorporate it before adding liquid.

Wine: Scrape the pot as you pour in the wine so the browned bits join the soup, then give it about 5 minutes to reduce.

Seasoning: The beef broth, bay leaf and dried thyme simmer together for 30 minutes, allowing the flavours to mingle.

Getting the bread and cheese right

Toasted baguette: Bake the slices at 200°C (400°F) for 5–7 minutes, until golden. Toasting helps them hold their shape when placed on the soup.

Gruyère: Shred the cheese and spread it generously over the bread. Grill the assembled bowls for 2–3 minutes, watching closely as the cheese melts and bubbles.

Timing the cooking

The onions take the longest, so allow the full 30–40 minutes and stir occasionally while they cook. The soup then simmers uncovered for 30 minutes.

Toast the baguette while the soup simmers, then assemble the bowls just before grilling. The stated total time is 75 minutes, though the onions may take up to 40 minutes.

Serving the soup

Serve the bowls hot, straight after the cheese has melted. The soup is filling enough to serve as a light main, or you can offer smaller bowls as a starter.

A simple green salad alongside gives the meal a fresh contrast to the rich broth, toasted bread and cheese.

Recipe notes & tips

• Slice the onions evenly so they cook at a similar rate.
• Stir the onions occasionally and keep the heat moderate to help them caramelise without scorching.
• Scrape the browned bits from the pot when adding the wine.
• Use oven-safe bowls for the final grilling step.
• Keep an eye on the bowls under the grill, as the cheese can brown quickly.

Variations

• Use vegetable broth: Replace the beef broth with vegetable broth for a meat-free version.
• Choose another melting cheese: Use a similar melting cheese if Gruyère is unavailable.
• Add fresh thyme: Swap dried thyme for fresh thyme to give the broth a fresh herbal note.
• Make it alcohol-free: Use extra broth in place of the white wine.
• Serve without grilling: Ladle the soup into bowls and serve the toasted baguette and cheese alongside.

Common mistakes to avoid

• Rushing the onions: They need 30–40 minutes to caramelise; keep cooking until deeply golden and tender.
• Leaving the onions unattended: Stir occasionally so they do not catch on the bottom of the pot.
• Skipping the scrape: Lift the browned bits with the wine to bring their flavour into the soup.
• Using untoasted bread: Toast the baguette until golden so it is less likely to turn soggy straight away.
• Walking away from the grill: Watch the cheese closely and remove the bowls once it is melted and bubbling.

How to store

Store leftover soup, without the bread and cheese topping, in a covered container in the fridge for up to 3 days. Reheat until hot, then toast fresh baguette, assemble the bowls and grill with Gruyère just before serving.

Frequently asked questions