Classic French Onion Soup with Cheesy Baguette Croutons

French

This homemade French onion soup, with slowly caramelised onions and a fragrant broth, warms up chilly evenings, topped with crispy cheese-topped bread and deep comforting flavours, perfect as a cosy starter or a light yet satisfying meal for family dinners.

Homemade French Onion Soup : Alcohol Free

I absolutely love French onion soup, that cosy bistro classic you “have” to know how to make properly to really appreciate it.

For years, I only ordered it in a little French café in London, always with a steaming bowl under its golden, bubbling cheese crust.

My husband and children never understood why I liked it so much, and I never dared try it at home in case it disappointed me.

One day I finally gave it a go and realised it’s nothing like just boiling onions in water.

The magic comes from slowly caramelising the onions and using a good chicken stock.

Now I make my own stock in big batches, freeze it in bags and keep it ready for quick dinners.

The result is a fragrant, generous soup that’s every bit as good as the one from the restaurant.

Ingredients for a perfect French onion soup

• 1.5 kg onions : Ideally yellow or sweet onions, they caramelise beautifully and give the soup a soft, rich flavour.
• 3 tablespoons butter : Adds depth and helps the onions brown without sticking. You can mix in a little oil if your pan tends to burn.
• 3 tablespoons flour : Lightly thickens the soup and gives it a silky texture. Let it cook for a minute or two with the onions to remove any raw flour taste.
• 2 litres chicken stock : This is the aromatic base of the soup. Use a flavourful stock that fully covers the onions and can simmer to develop even more taste.
• Salt and black pepper : Season at the end, especially if your stock is already salty. Freshly ground pepper lifts the flavour nicely.
• 1 pinch ground nutmeg : A warm, gentle note that deepens the taste without overpowering the onions.
• 1 baguette : Slightly stale is ideal: the slices hold their shape better and soak up the soup without falling apart.
• 150 g grated cheese : Emmental, Comté or Gruyère, any cheese that melts well and browns beautifully under the grill.
• Homemade chicken stock (ideal option) : If you can, cook a big batch in advance and freeze it in portions. It’s less salty, more aromatic and makes everyday soups taste special.

Step-by-step: how to make French onion soup

1. Melt the butter : Heat a large heavy-based pot over medium heat and melt the butter until it foams slightly.
2. Soften the onions : Add the onions, finely sliced. Stir to coat them in butter, then cook over medium, low heat, stirring regularly.
3. Caramelise the onions : Continue cooking until the onions are soft, golden and lightly caramelised. They should be nicely browned but never burnt. If the bottom catches, lower the heat and add a splash of water to deglaze.
4. Add the flour : Sprinkle the flour evenly over the onions, stirring constantly. Cook for 1-2 minutes to get rid of the raw taste and form a light roux.
5. Pour in the stock and season : Gradually add the chicken stock while stirring to avoid lumps. Add salt, black pepper and the pinch of nutmeg.
6. Simmer gently : Bring to a gentle boil, then reduce the heat. Let the soup simmer for at least 30 minutes, stirring occasionally so the flavours develop fully.
7. Adjust the consistency : If the soup is too thick, thin it with a little extra stock or water. If it’s too thin, simmer a bit longer to reduce.

French onion soup Video

Tips for perfectly caramelised onions

• Keep the heat medium-low: patience is key to colour without burning.
• Stir often and scrape the bottom of the pan to release all the flavourful brown bits.
• Add tiny splashes of water if the onions stick too much.
• Stop cooking when they’re soft, glossy and deep golden, not dark brown or black.

Which Stock and Cheese Work Best?

Stock :

• Homemade chicken stock: The most flavorful option and ideal for this recipe.
• Stock cubes or powdered stock: Absolutely fine, just choose a low-salt version and adjust seasoning at the end.
• Vegetarian option: Use a rich, well-flavoured vegetable stock instead.

Cheese :

• Emmental, Comté, Gruyère: Classic choices that melt beautifully and brown nicely under the grill.
• Mozzarella + a little grated Parmesan: Gives extra “stretchy” cheese on top with a more pronounced flavour.
• Stronger cheeses (mature Emmental, Beaufort): Perfect if you want a soup with a bolder, more intense cheesy taste.

Storing and Reheating French Onion Soup

– In the fridge

• Let the soup cool completely before storing.
• Pour it into an airtight container.
• It will keep in the fridge for 2 to 3 days.

– In the freezer

• Freeze only the soup (without bread or cheese).
• Put it into freezer-safe containers or bags.
• You can keep it for 2 to 3 months.

– Reheating

• Reheat gently in a saucepan over low heat, stirring from time to time.
• Add a little water or stock if the soup has thickened in the fridge or freezer.
• Make the cheesy bread topping fresh at the last minute so it stays crispy.

Variations of French Onion Soup

– Lighter version : Serve the soup with little or no cheese, and replace part of the butter with olive oil for a lighter finish.

– Extra-gratinated version : Pour the soup into oven-safe bowls, add the bread and cheese on top, then brown it directly in the oven until bubbling and golden.

– With a touch of white wine : Deglaze the caramelised onions with a splash of dry white wine before adding the stock for a deeper, more complex flavour.

– Herb-infused version : Add a bouquet garni (thyme, bay leaf) while the soup simmers, then remove it before serving.

– Vegetarian option : Use vegetable stock instead of chicken stock, and choose plant-based cheese or skip the cheese entirely.

Other soups to try

• Creamy Roasted Vegetable Soup
• Roasted butternut Squash soup
• Easy creamy mushroom soup
• Chorba frik (Algerian lamb and freekeh soup)