I love this cozy luxurious French Onion Soup.
Slow-cooked caramelized onions, simmered with rich beef stock and topped with melted-Gruyere-toast croutons.
The onions mellow and gain a rich sweetness as they cook down – adding so much flavour to this glorious soup.

Close-up of French Onion Soup in a white bowl on a wooden table next to a beige napkin. There is a gold spoon sticking out of the bowl. There is a further bowl and two spoons just in shot at the top of the image.
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I’ve waited far too long to put this recipe on the blog!

I was waiting for Chris to sharpen the knives so I could slice up the SIX onions that go into this soup.
It might sound like a lot for a recipe that serves four people, but they cook down and mellow beautifully, so they’re a little sweet with tiny bit of a nutty undertone.

You want to get a really good caramelisation going for maximum flavour, so those onions need to be cooked low and slow in plenty of butter.

  1. I use about 6 tablespoons of butter (plus a splash of oil) and cook the onions for about 45-55 minutes until they’re lovely and golden.
  2. We then add a little garlic and some white wine for depth of flavour.
  3. Bubble the wine until it’s nearly all evapourated, then we stir in flour – which helps to thicken the soup slightly.
  4. Next in goes plenty of good quality beef stock and a splash of Worcestershire sauce.
  5. Everything is simmered for a further 30 minutes, before the soup is ladled into bowls and topped with gooey Gruyere cheese croutons.

Check out the recipe card at the bottom of this post for full ingredients and instructions.

👩‍🍳PRO TIP Be sure to stir the onions regularly so they don’t ‘catch’ on the bottom of the pan when you’re cooking them.

A spoonful of cheese-topped-baguette-slice being taken from a bowl of French Onion Soup. The soup is in a white bowl on a wooden table. There are two further bowls in the background.

🍽️ Soup Bowls

I love to serve this soup in classic white French Onion Soup bowls. I bought these soup bowls (<– affiliate link) from Amazon.
Be sure to check that your soup bowls are grill-proof (broiler-proof in the USA) if you’re intending to melt the cheese directly in the bowls.

Three bowls of French Onion Soup on a wooden table. The soups are in white bowls and there is a beige napkin under the front bowl of soup. Each soup is topped with a little fresh thyme.

If you’re wondering whether I cried when chopping so many onions, the answer is no!
I wear contact lenses which makes me immune to the effects of all but the very strongest onions!

Overhead shot of three bowls of French Onion Soup in white bowls. The bowls are on a wooden table next to a beige napkin. There is a gold spoon sticking out of the bowl at the front of the image.

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5 from 4 votes

French Onion Soup

Cozy French Onion Soup. Slow-cooked caramelized onions, simmered with rich beef stock and topped with melted-Gruyere-toast croutons.
Prep Time: 30 minutes
Cook Time: 1 hour 35 minutes
Total Time: 2 hours 5 minutes
Servings: 4
Course: Dinner
Cuisine: French

Ingredients

Soup:

  • 90 g (6tbsp) unsalted butter
  • 1 tbsp oil
  • 6 medium yellow/brown onions about 1.2kg/2.6lbs, peeled, halved and thinly sliced
  • ½ tsp salt
  • 1 tsp black pepper
  • 3 cloves minced garlic
  • 180 ml (3/4 cup) white wine
  • 2 tbsp plain (all-purpose) flour
  • 1.5 litres (a splash over 6 cups) good quality strong beef stock *See note
  • 1 tbsp Worcestershire sauce

Cheese Crouton Topping:

  • 1 small baguette sliced into 2cm (3/4 inch) slices (we need 8 slices)
  • 100 g (1 packed cup) grated Gruyere cheese
  • fresh thyme leaves for garnish
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Instructions 

  • Add the butter and oil to a large Dutch oven or heavy-based saucepan. Heat over a medium-to-low heat.
    90 g (6tbsp) unsalted butter, 1 tbsp oil
  • When the butter has just melted, add the sliced onions, salt and pepper.
    6 medium yellow/brown onions, 1/2 tsp salt, 1 tsp black pepper
  • Cook, uncovered, for about 45-50 minutes, stirring occasionally at first, then often in the last 15-20 minutes (to stop the onions 'catching' on the bottom of the pan), until the onions are golden brown and caramelised. Be sure to keep a close eye on the onions, especially in the last 20 minutes, as you don't want them to burn at all. Turn down the heat a little if you're worried they'll burn.
  • Add the garlic and cook for one minute, whilst stirring.
    3 cloves minced garlic
  • Add the wine to ‘deglaze’ the pan and pick up all of those flavourful bits. Turn up the heat to medium-high and cook for about 5-8 minutes, stirring often until almost all of the liquid has evaporated and you can no longer smell the wine.
    180 ml (3/4 cup) white wine
  • Turn the heat back down to medium and stir in the flour. Cook for one minute, stirring constantly.
    2 tbsp plain (all-purpose) flour
  • Add the stock and Worcestershire sauce. Stir together, turn up the heat and bring to the boil.
    1.5 litres (a splash over 6 cups) good quality strong beef stock, 1 tbsp Worcestershire sauce
  • Turn the heat down to a simmer, stir again and place a lid on the pan. Simmer for 30 minutes. After 30 minutes, taste and add a little more slat if required (this wil depend on the saltiness of your stock).
  • When the soup is nearly ready, start on the cheese baguette slices/croutons.

Method 1 – Melting the cheese directly in the bowls

  • Once the soup is ready, ladle out into grill(broiler)-safe bowls.
  • Top each bowl with two of the baguette slices. Divide the grated Gruyere between the bowls, sprinkling it all over the soup and bread.
    1 small baguette sliced into 2cm (3/4 inch) slices, 100 g (1 packed cup) grated Gruyere cheese
  • Place the bowls on a tray under the grill (broiler) and slide under the heat.
  • Grill for 2-4 minutes, until the cheese is melted and bubbling.
  • Carefully remove the bowls (they’ll be VERY hot) and serve sprinkled with fresh thyme leaves.
    fresh thyme leaves for garnish

Method 2 – Melting cheese on the crouton separately

  • Toast the baguette slices on both sides under the grill (broiler) until lightly browned.
    1 small baguette sliced into 2cm (3/4 inch) slices
  • Once the baguette slices have been lightly browned under the grill (broiler), sprinkle them with the Gruyere and place back under the grill.
    100 g (1 packed cup) grated Gruyere cheese
  • Toast until the cheese is melted and bubbling.
  • Ladle the soup out into bowls and place two slices of the cheese toasts on top of each bowl.
  • Sprinkle with fresh thyme leaves and serve.
    fresh thyme leaves for garnish

Notes

Beef Stock
3-4 Knorr rich beef stock pots make a good strong stock. Essential cuisine beef stock/glace is also one of my favourites.
Is the soup thick?
The soup thickness is slightly thicker than water, but not as thick as gravy. 
Can I freeze it?
Yes, you can freeze the soup, but not the cheese crouton.
Make the soup, then cook and freeze in portions in airtight containers.
Defrost overnight in the refrigerator and reheat in a pan until piping hot.
Nutritional information is approximate, per serving.
 

Nutrition

Calories: 478kcal | Carbohydrates: 31g | Protein: 13g | Fat: 31g | Saturated Fat: 17g | Polyunsaturated Fat: 2g | Monounsaturated Fat: 10g | Trans Fat: 1g | Cholesterol: 76mg | Sodium: 1852mg | Potassium: 396mg | Fiber: 3g | Sugar: 10g | Vitamin A: 809IU | Vitamin C: 13mg | Calcium: 334mg | Iron: 2mg

Nutrition information is automatically calculated, so should only be used as an approximation.

Some of the links in this post may be affiliate links – which means if you buy the product I get a small commission (at no extra cost to you). If you do buy, then thank you! That’s what helps us to keep Kitchen Sanctuary running. The nutritional information provided is approximate and can vary depending on several factors. For more information please see our Terms & Conditions.

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Hi, I'm Nicky and I love to cook! I want to share with you my favourite, delicious family friendly recipes. I want to inspire you to create fantastic food for your family every day.

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Comments

  1. Caroline says:

    5 stars
    And I’m making this soup again (lost count of how many times I’ve made it) – it just gets better & better! So flavoursome- so worth all the prep/cooking 🤩

  2. Caroline says:

    5 stars
    I have made French onion 🧅 soup many times before which has always been good! This recipe is very good and definitely a keeper. Bit time consuming preparing the many onions and also the cooking but well worth the effort to achieve the beautiful sweet flavours! And the best bit is the gooey Gruyère toast soaked in the soup! I am a big fan!!! 😋

  3. Steve Harbinson says:

    5 stars
    Gonna have to leave the bedroom window open tonight!!! , a real deep creamy soup, gotta do croutons, gryere instead of cheddar next time 😋

  4. James Goacher says:

    5 stars
    I LOVE French Onion Soup but I have never cooked it. I am put off a little/lot by the 45-50 mins of caramalisation. I have seen Slow Cooker versions but have been sceptical as I watched a Cooking Video years ago which went through the steps you have outlined.
    BUT you have convinced me to bite the bullet. The Freezing option clinched it. Just got to buy some Gruyere, and some Onions, and some Wine, don’t normally drink White wine, Oh and some Baggette. I have a Dutch Oven 🙂