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Keto French Onion Soup

4.98 from 448 votes
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Keto French Onion Soup is a low-carb version of the traditional classic French onion soup recipe.

Sweet caramelized onion simmered into a beef broth with cheesy keto bread croutons topped with Swiss cheese.

Is French Onion Soup Keto-Friendly?

If you wonder, is French onion soup keto-friendly? Well, no! A traditional French onion soup is not keto-approved.

Below I listed all the ingredients and reasons why you shouldn’t eat a traditional French onion soup on keto:

  • Sugar. a classic French onion soup requires onions that are caramelized in sugar. Sugar is your worst enemy on keto since it is pure carbs. Only 10 grams is 10 grams of net carbs!
  • White wheat flour. this is used to help thicken the soup, and like sugar, flour is pure carbs, so not for you on keto!
  • White wine. White wine is used to deglaze the onions. You can have some dry white wine on keto if used in moderation, but unfortunately, the classic French onion soup uses quite a good amount, which brings the carbs very high.
  • Croutons. A classic French onion soup is always topped with lots of toasted French bread. Again, regular bread is not keto-friendly as it is made with wheat flour, high in carbs.

So, as you can see, you can’t eat a classic onion soup recipe.

But let me show you how French onion soup and keto can work together!

Why You’ll Love This Recipe

This Keto French Onion Soup is delicious, it tastes just like the classic recipe, but it’s also:

  • Gluten-Free
  • Nut-Free
  • Egg-Free
  • Low-Carb
  • Keto-Friendly
  • Ready In Under 30 Minutes
Keto French onion soup

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How To Make Keto French Onion Soup

There are a few necessary tweaks to make an onion soup keto-friendly.

Let me show you how to select the ingredients to make a keto low-carb French onion soup.

Soup Ingredients

  • White onion. Onions are naturally high in carbs, so I use fewer onions in my keto version of the French onion soup. Still, a good enough amount to bring texture and flavor. Don’t use red onions. They are higher in carbs, and the soup would be very sweet.
  • Erythritol. It’s the swap to sugar, and it is a 100% keto-friendly keto sweetener that can caramelize onion just as well without adding any carbs.
  • Beef bone broth. Also known as keto beef stock sometimes, it’s 100% keto-friendly, so you are safe here. If you want to make a vegetarian French onion soup, swap beef bone broth for vegetable broth.
  • Xanthan gum. This is your thickening agent. It contains barely any carbs and replaces high-carb flour found in the traditional French recipe.
  • White wine. Not all white wines are keto-friendly. You must use dry white wine like Sauvignon blanc. I also reduced the amount in this recipe to keep the net carbs per serving under control while having the tangy wine flavor.
  • Bay leaves. The secret French herb to any good French onion soup and many French dishes.
  • Thyme
  • Salt. Optional if your beef broth is already high in salt.

Preparing The Soup Broth

It is super easy to make an onion soup. First, heat the butter, add finely sliced white onion, and cook for 20-25 minutes until soft, brown, and fragrant.

Then, add erythritol and salt to caramelize the onion. Finally, deglaze the onions with dry white wine and beef broth.

French onion soup

Choosing The Croutons

The best part of French onion soup is these crunchy croutons and broiled bubbly cheese on top!

You don’t want to miss this even on keto so let me share my tricks to making quick keto croutons to add on top of your soup.

A traditional French onion soup is not topped with small bread croutons but with a thin French baguette slice.

French people eat baguettes daily, and the slice of baguette on top of the onion soup is most of the time a stale baguette that has hardened on the kitchen countertop.

Then, we slice thin pieces of hard baguette and toast it in a bread toaster or oven to get it very hard and crispy.

Finally, we spread fresh butter on the bread and rub a fresh garlic glove to flavor it.

This is then added on top of the onion soup and grated cheese: usually Emmental, Gruyere, or Swiss cheese, and broil in the oven.

is French onion soup keto

Making Keto Croutons

Of course, you can’t eat regular French bread or croutons on a keto diet. But I have a few solutions for you to mimic crispy croutons into your soup.

Make A Quick Keto Microwave Bread

My favorite option is to make my 90-second keto microwave bread recipe in a tall cylinder coffee mug. This keto recipe mimics the baguette shape.

Then, release the bread cylinder and slice it into thin bread slices. The slices will be very soft so bring them into a bread toaster on high until crispy.

Then, spread butter on the toasted bread slices and rub fresh garlic on the bread – onions and garlic are delicious, don’t skip! 

Finally, top your keto onion soup bowl with a slice of this keto crouton recipe, add cheese and broil!

Et voila! You made a keto French onion soup.

If someone asks you if you can eat French onion soup on a keto diet, you can proudly answer yes, and serve this yummy recipe!  

Keto croutons

Using store-bought crouton alternatives

If you don’t feel like baking, use some of the options below to mimic croutons into your keto soup:

  • Pork rinds: that’s the closest alternative to croutons, and it contains zero carbs, so it’s a great addition to your keto meal.  
  • Toasted seeds: like sunflower or pumpkin seeds.
  • Parmesan crisp
French onion soup keto

Storing French Onion Soup

Onion soup stores very well in the fridge for up to 5 days in a sealed container.

You can rewarm the soup in a saucepan or microwave. Then, broil in the oven with shredded cheese.

French onion soup and keto

Frequently Asked Questions

How Much Keto French Onion Soup Can I Eat?

This recipe serves 8 bowls. The serving size is 1 cup of soup and 1 slice of keto crouton and cheese.

The entire low-carb onion soup bowl, including bread slices, contains 7.8 grams of net carbs or 6.1 grams of net carbs without the keto bread.

Can I Replace The Wine?

Yes, you can use Worcestershire Sauce instead. But keep in mind that all the alcohol from the wine evaporates as the soup cooks.

Can I Skip The Xanthan Gum?

Yes, you don’t have to use xanthan gum it’s not absolutely necessary. The texture will be slightly more watery, but it’ll be delicious.

can I have French onion soup on keto

Enjoy the lovely Keto French recipe, and don’t forget to leave me a comment below if you made it and review it!

You can also follow me on Pinterest for more keto inspiration.

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Low carb French onion soup

Keto French Onion Soup

6.1gNet Carbs
This Keto French Onion Soup is the keto and gluten-free version of the popular French onion soup.
Prep: 30 minutes
Total: 30 minutes
Yield: 8 people (1 cup = 1 serving)
Serving Size: 1 soup (1 cup)
4.98 from 448 votes


For the keto bread toast

This recipe may contain Amazon or other affiliate links. As an Amazon Associate I earn from qualifying purchases.


  • In a large pot, heat butter and onions over medium heat.
  • Cook onion until they soften- about 2 minutes, then add salt and erythritol.
  • Reduce to medium/low heat and continue cooking/stirring the onion until they become fragrant and golden brown. This takes about 20-25 minutes. Make sure you stir often to avoid burning the onion.
  • Sprinkle the xanthan gum all over the cooked onion, add beef stock, low-carb white wine if used (or more beef broth if preferred), dried thyme, and bay leaves. Cover and simmer for 30 minutes.

Keto bread crouton

  • Meanwhile, prepare the keto croutons. Make 1 batch of my 90-second keto microwave bread recipe. Make sure you bake the recipe into a tall cylinder shape coffee mug (microwave safe!)
  • Cook your keto bread in the microwave following the recipe here. Release the bread cylinder from the mug, cool for 1 minute to steam out (this also avoids burning yourself), then cut into 4 even slices. You can repeat this bread recipe to make 4 more croutons if you intend to serve 8 soup bowls.
  • Bring each bread slice into a bread toaster on high and toast until crispy on both sides. Set aside on a plate to cool.
  • Preheat oven to 350°F (180°C). When the oven is hot, turn to broil mode.
  • Remove bay leaves from the soup and discard.

Serve the soup

  • Ladle soup into 8 oven-proof soup bowls – 1 cup is 1 serving.
  • Brush some butter on top of each slice of toasted keto bread. Rub a fresh garlic glove on the bread slices to flavor the bread.
  • Place 1 toasted bread slice on top of each bowl.
  • Cover the top of each soup bowl with 1/3 cup of grated French gruyere.
  • Broil in the oven until the cheese is brown.
  • Serve immediately.


  • Store leftover soup in an airtight sealed container in the fridge for 3-4 days.


The net carbs in the nutrition panel below don’t include the slice of 90-second bread recipe on top of the soup. Add 1.6 grams of net carbs per slice, if the lookbread is cut into 4 slices or 1 gram if you cut the bread into 6 slices.
Follow my bread recipe here and bake it in a tall coffee mug to create keto croutons that looks like French baguette slices.

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Nutrition1 soup (1 cup)
Yield: 8 people (1 cup = 1 serving)


Serving: 1 soup (1 cup)Calories: 202.7 kcal (10%)Carbohydrates: 7.4 g (2%)Fiber: 1.3 g (5%)Net Carbs: 6.1 gProtein: 10.3 g (21%)Fat: 14.2 g (22%)Saturated Fat: 8.5 g (53%)Cholesterol: 42.3 mg (14%)Sodium: 881.6 mg (38%)Potassium: 227.8 mg (7%)Sugar: 3.2 g (4%)Vitamin A: 409.6 IU (8%)Vitamin C: 5.4 mg (7%)Calcium: 278.6 mg (28%)Iron: 0.6 mg (3%)
Carine Claudepierre

About The Author

Carine Claudepierre

Hi, I'm Carine, the food blogger, author, recipe developer, published author of a cookbook and many ebooks, and founder of Sweet As Honey.

I have an Accredited Certificate in Nutrition and Wellness obtained in 2014 from Well College Global (formerly Cadence Health). I'm passionate about sharing all my easy and tasty recipes that are both delicious and healthy. My expertise in the field comes from my background in chemistry and years of following a keto low-carb diet. But I'm also well versed in vegetarian and vegan cooking since my husband is vegan.

I now eat a more balanced diet where I alternate between keto and a Mediterranean Diet

Cooking and Baking is my true passion. In fact, I only share a small portion of my recipes on Sweet As Honey. Most of them are eaten by my husband and my two kids before I have time to take any pictures!

All my recipes are at least triple tested to make sure they work and I take pride in keeping them as accurate as possible.

Browse all my recipes with my Recipe Index.

I hope that you too find the recipes you love on Sweet As Honey!

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    13 Thoughts On Keto French Onion Soup
  1. 5 stars
    Switched to a keto diet to help control my husband’s diabetes (unbelievable results!) but do miss some favorite dishes.
    Didn’t think I could make french onion soup again – this recipe proved me wrong…
    Took way longer to caramelize the onions – about 45 minutes – but worth the effort. And the microwave bread is definitely a winner.
    Thank you so much for this recipe.

  2. 5 stars
    This soup is amazing! I did cook my onions over low heat for much longer until they just started to carmelize, like I used to do pre-keto with my old recipe. And I did add the sweetener, which was something new for me. I’m not really sure if it’s necessary. I didn’t have wine but just added a splash of Worcestershire sauce. This soup came out sooooo good, I can’t wait to have leftovers tonight! It is AWESOME, so easy to make and so rich and flavorful.

  3. This is amazing. Big hit with the fam! I didn’t have the Xanthan Gum. And I used Keto Worcestershire sauce instead of wine. Used Keto white bread and 2 Swiss slices per bowl.
    But I love the Keto bread in the recipe!

  4. 5 stars
    I was really craving French onion soup & had no idea how to make it. Just finished your recipe and it’s DELISH! Big hit with the hubby too. This was quick, simple and incredibly tasty. Thanks for sharing!

  5. 4 stars
    Can’t wait to make this tonight! I don’t have thyme & need to buy some. Do you use ground time or dried thyme (pieces)? Wondering which is more useful? Thanks for the recipe!!

  6. 5 stars
    Made it tonight and it was spot on perfect comfort food! Simple ingredients and very easy to make. I omitted the croutons to save carbs, but might melt cheese on it tomorrow. Thanks for sharing this. I will be trying out more of your recipes soon!

  7. Hi Carine, I am planning on making this recipe tonight! Unfortunately, I don’t have any xanthan gum saved. Do you have any low carb recommendations I could use as a substitute? Otherwise, I could try and go buy some if it is absolutely needed.

    Look forward to hearing from you!

  8. There are way too many ingredients in your soup. My absolute favourite French Onion Soup is in the NZ Edmonds Cook Book. It does have sugar, but I don’t put any in my soup. Nor do I put in the sherry. I don’t eat red meat, so leave out the beef stock and put in vegetable. Whenever onions are in season I put in the 5 ingredients of butter, onion, stock, salt & pepper and happily have soup for many nights.

    • I am not sure what you mean, this soup contains 9 ingredients, including 5 that are herbs or flavoring. You can obviously these 5 herbs but your soup will lack in flavor. Here my goal is to share an adaptation of the classic French soup recipe I used to eat as a kid (I am French). I am sorry you don’t appreciate it. Enjoy the blog, XOXO Carine

      • It’s extremely rude to promote another’s sourced recipe in a review.
        Say you didn’t like it and move on. (Insert eye roll)


The recipes, instructions, and articles on this website should not be taken or used as medical advice. You must consult with your doctor before starting on a keto or low-carb diet. The nutritional data provided on Sweetashoney is to be used as indicative only.

The nutrition data is calculated using WP Recipe Maker. Net Carbs is calculated by removing the fiber and some sweeteners from the total Carbohydrates. As an example, a recipe with 10 grams of Carbs per 100 grams that contains 3 grams of erythritol and 5 grams of fiber will have a net carbs content of 2 grams. Some sweeteners are excluded because they are not metabolized.

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