This super tasty Keto French Onion Soup is coming at you with a rich, flavorful broth, sweet strands of caramelized onion, and a cheesy crouton topper. Seriously – what more could you ask for??? (Nevermind, don’t answer that…..)
You won’t find a lot of recipes out there for Keto French Onion Soup – I know, I checked. The reason is that onions actually contain quite a bit of carbs, so it’s a challenge to keep the overall net carbs down in a soup that’s…well…pretty much made of just onions.
I decided to tackle it anyway, because I LOVE French Onion Soup, and I knew there had to be a way to minimize the carbs to make it low carb and keto friendly.
Frequently Asked Questions
I had to make a few concessions to get this to work. There are a little less onions in this Keto French Onion Soup than you might find in a more traditional version.
That’s OK though, because the delicious thyme flavored crouton soaks up the broth and makes this soup plenty hearty – and there are more than enough onions in there to get some in every spoonful.
These toppers though? I’m not sure what to call them – not quite a toast, not really a crouton, so…???? Your ideas welcome.
What I can tell you is that they make the perfect raft for the copious amounts of cheese you are going to add before digging in to this low carb French onion soup!
I would also add that these lil toppers are really, really versatile in their own right. I had a bunch in my freezer that I’ve since used to garnish other soups and stews to create a dumpling/biscuit/pie crust situation that was just perfection.
I’ve also used these toppers to put my bacon and egg on in the morning like a little open-faced breakfast sandwich. There’s a lot you can do with these – so much so that I almost gave them their own post on the blog, and I still might down the road.
All told, you can have a generous portion of this Keto French Onion Soup, complete with the topper and cheese and still come in at 10g net carbs.
It might sound like a lot when you’re shooting for only 20g net carbs per day, but it’s totally doable if you have almost no carbs with breakfast (bacon, eggs, avocado, and coffee are my go to) and a carb light lunch like tuna salad with romaine leaves.
Now you’ve got over 15g’s left for dinner which leaves plenty for this delicious and filling onion soup (and a glass of wine to go with it if you’re splurging.)
If you’re a French Onion Soup lover like me, then you’re going to find a way to make it work – and I promise you’ll be glad you did!
Here’s a few questions you might have that I’ll answer preemptively below:
Is French Onion Soup keto friendly?
As I mentioned, it can be a challenge to keep the carbs down in a French onion soup, but this version is absolutely keto friendly. Here is the breakdown of the nutrition info by component ( I will also supply this in the notes section of the recipe card.) If you want to keep the carbs down you can omit the topper, but it won’t be as filling and satisfying in my opinion.
Keto French Onion Soup: 113 calories, 7g fat, 8g carbs, 1g fiber, 7g net carbs, 3g protein
Thyme Topper: 245 calories, 19g fat, 5g carbs, 2g fiber, 3g net carbs, 16g protein
Cheese: 60 calories, 5g fat, 0g carbs, 0g fiber, 3g protein
Why do they call it French Onion Soup?
Fun fact – it’s called French onion soup because it has been common in France for centuries, where onions were cheap and plentiful during hard times. It eventually became a staple of Paris restaurants during the 18th century (where they just call it onion soup or “soupe à l’oignon”) and gained popularity as a first course served with toast and cheese, which is how it is still most commonly served today.
Now you know…
Is this onion soup vegetarian or vegan?
Typically, French onion soup gets its rich flavor from beef broth, which is what I used here. If you don’t eat beef you can substitute chicken broth for a lighter flavor. If you want to make this soup vegetarian or vegan, you can substitute a vegetable broth or stock, but the carbs may be a few grams higher than a broth made with meat. This recipe also includes Worcestershire sauce, which contains anchovies. You can replace it with an equal amount of coconut aminos for a similar flavor that is completely plant-based.
Can I use any kind of onion in French Onion Soup?
In a word, yes. I used yellow onions, which are traditionally used and give it a nice mellow flavor, but you can use white onions or even red onions if that’s what you have on hand – it will make very little difference in the end result.
Can I omit the wine in this Low Carb French Onion Soup?
Also yes. The white wine called for adds a subtle flavor that can be replicated by replacing it with an equal amount of water, and a teaspoon of balsamic or red wine vinegar.
What cheese can I top this low carb onion soup with?
Traditionally a French cheese like Comte, Gruyere, or even Swiss would be used to top a French Onion Soup – but if you can’t get it or aren’t a fan of the flavor, a mild cheese like mozzarella or muenster will work just as well. Cheddar will definitely stand out and compete with the flavor of the soup so I’d use it as a last resort unless you are looking for that kind of effect.
Ok, that should do it on the questions but if I’ve missed any let me know in the comments and I’ll answer them there and add them to this FAQ if necessary.Print
Keto French Onion Soup – Low Carb
- Total Time: 1 hour 30 minutes
- Yield: 8 servings 1x
- Diet: Diabetic
This super tasty Keto French Onion Soup is coming at you with a rich, flavorful broth, sweet strands of caramelized onion, and a cheesy crouton topper. Vegetarian and gluten free options available.
For the soup:
- 3 tablespoons olive oil
- 2 tablespoons butter
- 4 cups thinly sliced yellow onions
- 1 teaspoon kosher salt
- 1/2 teaspoon ground black pepper
- 1 teaspoon minced garlic
- 1/3 cup dry white wine
- 1 tablespoon fresh thyme leaves (or 1 teaspoon dried)
- 3 bay leaves
- 2 cups water
- 8 cups beef stock (or vegetable stock for vegetarian)
- 1 tablespoon Worcestershire sauce (or coconut aminos for gluten free & vegetarian)
- 1 tablespoon granulated erythritol
- 8 slices Swiss or Gruyere cheese (to serve)
For the toppers:
- 1 batch Easy Keto Dough
- 2 tablespoons fresh thyme leaves or 1 bunch of thyme springs
To make the soup:
- Heat the oil and butter over low-medium heat in a large saucepan.
- Add the onions, salt, and pepper, and cook uncovered, stirring occasionally, for 30 minutes or until the onions are a deep golden brown.
- Add the garlic and cook for an additional 2 – 3 minutes, or until fragrant.
- Add the white wine, thyme leaves, and bay leaves, and cook for 5 minutes or until the liquid is reduced by half.
- Add the water, beef stock, Worcestershire sauce (or coconut aminos) and granulated erythritol (or other sugar sub) and simmer (not a rolling boil or you’ll have too much evaporation) uncovered over low to medium heat for 30 minutes.
- Remove the bay leaves, then taste and season with additional salt and pepper if desired. Keep warm until ready to serve, or refrigerate in an airtight container for up to 5 days. You can also freeze this for up to 3 months.
For the toppers:
- Preheat the oven to 375 degrees Fahrenheit.
- Divide the dough into 8 balls of equal size.
- Press into 4 inch discs (or whatever size your preferred soup bowls will accommodate.)
- Place the discs on a large parchment-lined baking sheet and press the thyme leaves or sprigs into the top of the dough.
- Bake for 15 minutes or a light golden brown. Remove and cool before storing in an airtight container in the refrigerator for up to 1 week, or in the freezer for up to 6 months.
To assemble and serve:
- If cold, heat the soup in a pot or the microwave before ladling into the serving bowls.
- Once hot, ladle the soup into oven proof bowls.
- Top with a thyme crouton and a slice of the cheese.
- Broil for 2 – 3 minutes, or until the cheese is melted slightly golden on top.
- Serve hot.
Approximate net carbs = 10g for the soup with cheese and crouton.
Approximate net carbs for just the soup = 7g
- Prep Time: 20 minutes
- Cook Time: 70 minutes
- Category: Keto soups
- Method: stovetop
- Cuisine: French
- Serving Size: 1 1/4 cups soup + 1 topper + 1 slice cheese
- Calories: 418
- Fat: 31g
- Carbohydrates: 13g
- Fiber: 3g
- Protein: 22g
Keywords: keto onion soup, keto French onion soup, low carb French onion soup
Love, love, love some French onion soup on a winters day (or any day!)
Melissa, I LOVE your recipes and can’t wait to try this. Have you ever made this onion soup in your Instant Pot? Just trying to speed up the process a bit. Thanks, another Ellen
Jen F says
I love French onion soup, I’m so excited to find a keto-friendly version!
Twanna Canada says
I’ve been searching for keto soups and I’ve missed french onion soup. Thanks for making a keto version – this will be added to my favorite recipe rotation.
Robyn Harris says
My all time fave soup! Even tastier now that you made it keto friendly. Great recipe, Mellissa! My family thoroughly enjoyed each spoonful. Thank you for sharing! 💕
Christine T. says
This was just incredible! I had never tried any of the keto breads or doughs and was nervous but the toppers came out perfect and were so easy to make. They held their texture in the soup but were tender enough to cut through with the spoon. I love FO soup and this was just a knockout. Thank you so much!
Mellissa Sevigny says
Thanks so much for taking the time to rate and comment Christine! I’m so glad that your firsts try at the keto toppers worked out perfectly!
When you cooked your onions, were you using a gas stove. My onions took longer to brown on a regular element at the heat you suggested.
Mellissa Sevigny says
Yes, I was using a gas stove when I made this recipe so it’s possible the burner was hotter for me.
I’ve followed low carb/Keto for years, but have recently had to make a change to counting saturated fats instead of carbs. :-(
What’s the beat way for me to determine the saturated fats in your recipes, which I have come to love?
Mellissa Sevigny says
You can check sites like My Fitness Pal where it may already be uploaded, or you can input the fat containing ingredients into a site like calorie king to find the saturated fat numbers.
Can I batch freeze this? Thank you so much for your wonderful recipes and beautiful website.
Mellissa Sevigny says
I don’t see why not Sue – then just heat and add the crouton and cheese right before serving!
Johanna W says
Girl. Get out of my head! I was just thinking about how to make french onion soup keto friendly!!!
Mellissa Sevigny says
Haha – perfect timing! 🙌🏻
Oh my! We made this soup the other night and my family couldn’t get enough! Thank you so much for this delicious recipe! It will be going into our dinner rotation.