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Keto French Onion Soup

Is French Onion Soup keto? It sure can be, and with this tried-and-true recipe you can get all your favorite flavors in a hearty bowl of goodness!

keto french onion soup topped with a cheesy layer
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Onions are higher in carbs – this is true – but with this technique for coaxing the most flavor out of the onions, you can user fewer onions and get fewer carbs.

I’ve been making this French Onion Soup this way forever – back to when I was a private chef long before I owned my own restaurant.

Want the secret to this amazing keto French Onion Soup recipe? Read on!

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What You Need To Make French Onion Soup Keto

  • A soup pot – but not a huge one.
  • A skillet
  • French onion soup bowls
  • Onions – of course! Yellow onions are just fine
  • Garlic – fresh is best!
  • Butter
  • Chicken broth – low or no sodium or use your homemade bone broth
  • Beef broth – low or no sodium
  • Bay leaf – 2 dried bay leaves
  • Fresh thyme – dried thyme will also work
  • 1/2 cup red wine (optional)
  • Cheese – go for gruyere to keep it authentic or use what you’ve got
  • Salt and pepper

So, Chef Jenn – What’s the Secret?

You’ve seen the ingredient list but what you might not have noticed is the combination of beef AND chicken broth.

Using ALL beef broth makes the soup too strong in flavor and overwhelms the delicate onion flavor.

Using just chicken broth doesn’t give the soup enough body. But when you combine them – well, magic happens!

Secret #2


Yup, that’s right – patience. It takes time to develop the flavors in this soup, and it all starts with caramelizing those onions to bring out all the natural sweetness in them.

How To Caramelize Onions

Add gobs of butter to a skillet. For this keto French Onion Soup recipe, we’re going to use 4 tbsp of butter.

Melt that butter until it is sizzling but not brown.

Add the sliced onions and turn the heat down to medium-low.

Now, cook those onions slowly in all that buttery goodness. You want them to be a dark golden brown but not burned. They should be moist and creamy without being crunchy and dried.

Low heat and lots of time will do the trick. Stir them frequently – all in all it should take about 30 minutes (or a bit longer) to get them properly caramelized.

How To Make French Onion Soup au Gratin

Au gratin literally means “with cheese.” So, topping this bowl of oniony soupy goodness with melted cheese is the perfect finish to this soup.

  1. Caramelize the onions (see above). Add the garlic for the last minute to cook it through.
  2. Deglaze the pan with the wine and let it sizzle for a minute or two (optional).
  3. Everything goes into a soup pot and let is simmer, covered, for about 20 minutes.
  4. Pull out the thyme sprigs and ladle into oven-safe bowls.
  5. Top with low-carb bread or a chaffle, cover in cheese, and pop it under the broiler for a few minutes until it is bubbly and brown. Enjoy your low-carb French Onion Soup!

Chef Jenn’s Tips To Make French Onion Soup Keto

  • Use regular yellow onions. Spanish or sweet onions have a higher sugar content and will have more carbs.
  • Don’t add the chaffle or bread until the very last minute or it’ll get soggy.
  • Use shredded cheese for the best melting.
  • Use proper French onion soup bowls. They’ve got wide openings for maximum cheesy coverage and are oven-safe so you can put them under the broiler to melt that cheesy goodness.
  • Make this a keto vegetarian soup recipe by using vegetable broth instead of the beef and chicken broth.

What To Serve With This Keto Onion Soup

I love a fresh salad topped with this fabulous Ranch Dressing with a bowl of soup, or if I’m especially hungry, I’ll nibble on toasty Sourdough Chaffles or theses keto cheese breadsticks.

Is This Keto Soup Recipe Freezer Friendly?


A BIG yes! I often have some of this in my freezer ready for when I’m craving a delicious bowlful of soupy goodness.

To freeze it, thoroughly chill the soup. Then, package it in freezer-safe containers for up to three months.

My favorite way to freeze saucy and soupy recipes is by using Souper Cubes! These amazing freezer-safe cubes are perfect for freezing portions of all my favorite soups, stews, and other saucy meals. I freeze them then pop them out and put the rectangular frozen blocks into a zipper-top freezer bag. It makes storing them SOOOO much easier!

Where can you find these Soup Cubes? You can order them from Souper Cubes – how cool is this?

souper cubes
Souper Cubes make freezing easy!

Reheat it on the stovetop or in the microwave.

Is French Onion Soup keto?

It sure is! Start with regular yellow onions, don’t add any sugar (French onion soup shouldn’t have sugar added to it anyway!), and limit the number of onions that you use to control the carbs. And of course, top it with a chaffle instead of bread.

What onions are best for French onion soup?

Yellow onions are what Chef Jenn uses. Sliced thin and caramelized in lots of butter, you won’t need to add any sugar because the natural sweetness in the onions will come out.

How long does it take to make French Onion Soup?

From start to finish, it takes a little over an hour to make this classic soup. It takes time to caramelize the onions, and then it all needs to simmer in the broth.

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Step By Step Process

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keto french onion soup in a white soup bowl with a second serving in the background
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5 from 4 votes

Keto French Onion Soup

A rich, savory broth and oodles of onions topped with a cheesy layer makes this a keto French Onion Soup not to be missed!
Course Soup, Soups & Stews
Cuisine European
Keyword easy soup, french, french onion soup, keto soup, onion soup
Prep Time 40 minutes
Cook Time 20 minutes
Total Time 1 hour
Servings 4 servings
Calories 316kcal
Author Chef Jenn


  • 3 cups onions sliced
  • 1 clove garlic minced
  • 4 tbsp butter
  • 1/2 cup red wine optional
  • 2 cups low sodium chicken broth
  • 2 cups low sodium beef broth
  • 2 sprigs freshy thyme or 1/2 tsp dried thyme
  • 2 bay leaves
  • 1 cup cheese shredded
  • 1/2 tsp salt
  • 1/4 tsp pepper


  • Add the butter to a skillet large enough to hold the onions. Melt the butter over medium heat and slowly caramelize the onions until they're dark brown and soft. Add the garlic and continue cooking for 1 minute. Set aside.
  • Deglaze the skillet with the red wine and let it simmer for 2 minutes, or deglaze the pan with 1/2 cup of the beef or chicken broth. Scrape all this into your soup pot.
  • Add the onions, thyme, bay leaf and remaining broth to the soup pot. Cover and simmer for 20 minutes.
  • Remove the sprigs of thyme and bay leaves and season the soup with salt and pepper. Ladle into bowls and top with a chaffle or low-carb bread and 1/4 cup of cheese. Pop under the broiler until hot and bubbly. Enjoy!


Please note: The nutritional values for this recipe do not include a chaffle or low-carb bread for topping your soup. Don’t forget to add that depending on what you choose to use.


Serving: 1cup | Calories: 316kcal | Carbohydrates: 14g | Protein: 13g | Fat: 22g | Saturated Fat: 13g | Trans Fat: 1g | Cholesterol: 60mg | Sodium: 828mg | Potassium: 591mg | Fiber: 2g | Sugar: 6g | Vitamin A: 637IU | Vitamin C: 9mg | Calcium: 244mg | Iron: 1mg | Net Carbohydrates: 12g

A Note on Nutritional Information

Nutritional information for this recipe is provided as a courtesy and is calculated based on available online ingredient information. It is only an approximate value. The accuracy of the nutritional information for any recipe on this site cannot be guaranteed. Erythritol carbs (sugar substitutes) are not included in the carbohydrate counts as they have been shown not to impact blood sugar, and they have zero calories and zero carbs. Net carbs are the total carbs minus fiber.

Chef Jenn’s Favorites

There’s even more keto goodness to love, and at the time of posting this recipe, the following are a few of Chef Jenn’s favorites:

about jenn

Hi, I’m Jenn!

I’m a cookbook author (Keto Soup Cookbook and Keto Diabetic Cookbook and Meal Plan) as well as a retired chef, recipe developer, and writer of this blog (that’s a lot of hats!). I embarked on a journey to create foodie-worthy Keto-friendly meals that any home cook can be proud of! No matter if you’re low-carb, no-carb, dirty, or strict Keto, there are recipes in Keto Cooking Wins for you and your family. Read more...

4 thoughts on “Keto French Onion Soup”

  1. 5 stars
    I used vegetarian broth and this soup was delicious! The onions were perfectly caramelized and well worth the wait to cook them properly.

  2. 5 stars
    Wow! This looks amazing and so delicious! My hubby and I are definitely going to love this recipe! I’m so excited to make this!

  3. 5 stars
    I don’t necessarily eat Keto, but I would still love this and can’t wait to make it. I like the idea of the blended broths and fewer onions.

5 from 4 votes

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