Keto French Onion Soup
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My keto French onion soup recipe features caramelized onions swimming in warm broth with crusty bread and melty cheese. It’s made with no flour, no thickeners, and only 3 grams of net carbs!
Keto French onion soup that rivals the classic
Low carb French onion soup isn’t the first thing people think to make, and it’s easy to see why.
I suppose it makes sense, considering the main ingredients in French onion soup are decidedly not keto-friendly (note: bread, wine, and a boatload of onions). Luckily, with a few low-carb substitutions and cooking down fewer onions, it can become a staple of any keto diet.
I swapped the baguette for a couple of my low carb bread options (I’ll share them below), and covered it with plenty of cheese. I’m a soup purist, and honestly, the rich beef broth and caramelized onions do all the heavy lifting. Here’s why I love it:
- Comfort food at its finest. We’re talking savory broth, sweet onions, toasted bread, and layer upon layer of melted cheese.
- Surprisingly easy to make. For how fancy this looks, I swear you could make it in your sleep. There’s no excessive prep work required!
Let’s make this together now.
Table of Contents
Key Ingredients
Here’s what you’ll need, along with my kitchen notes. Full measurements are in the recipe card below.
- Butter. I suggest using unsalted butter since we’re using salty ingredients. Remember, you can always add salt later.
- Onions. White onion is preferred, but yellow onions or sweet onions can also work, just not red onions (they won’t caramelize properly). Slice them finely (about 1/4-inch thick) so they caramelize evenly.
- Granulated sweetener. Just a pinch to balance out the salty flavors. I use allulose, since it dissolves exactly like sugar.
- Salt and black pepper. To taste.
- Beef broth. I prefer premade broth over bouillon cubes, as they tend to have fewer additives or excessive sodium. I also suggest double-checking the ingredients, as some brands add sugar.
- Worcestershire sauce. Adds a lovely complex flavor and enhances the meaty flavors.
For the toasted cheesy bread:
- Keto buns. Traditional French onion soups typically use sliced baguette. To replicate this, I’ve used thinly sliced keto hot dog buns. I’ve also tested this with thickly sliced keto bread and even keto rolls.
- Gruyère cheese. Another must for French onion soup! Always use freshly grated cheese; it has better flavor and melts smoothly. Can’t find gruyere? Use mozzarella, white cheddar, or Swiss cheese instead.
- Fresh thyme. To serve.
How to make keto French onion soup
Step 1- Prep. Preheat the oven to 200C/400F and line a large baking sheet with parchment paper.
Step 2- Sauté onions. Place a large soup pot over medium heat. Once hot, melt the butter. Add the sliced onions, sweetener, salt, pepper, and sauté for 8-10 minutes.
Step 3- Build the broth. Add the beef broth and Worcestershire sauce and bring to a simmer. Once simmering, cover the pot and let it simmer for 10 minutes.
Step 4- Prepare the cheesy bread. Slice the keto bread into six thick slices, then slice each in half. Place the twelve pieces of bread onto the prepared baking sheet. Sprinkle the cheese on top. Bake the bread for 6-8 minutes or until golden brown.
Step 5- Assemble. Ladle soup into small bowls. Add 1-2 pieces of the cheesy toast on top and sprinkle with extra cheese and thyme sprigs.
Arman’s recipe tip
Broil at the end. When time allows, I like to ladle the soup into oven-safe bowls and then place them in the oven on the broiler setting for 2-3 minutes. This crisps up the bread and helps the cheese get even more melty.
More keto soup recipes
Keto French Onion Soup
Ingredients
- 1 ounce butter
- 4 large onions thinly sliced
- 1/2 teaspoon allulose or any granulated sweetener
- 1/2 teaspoon pepper
- 32 ounces beef broth
- 3 tablespoons Worcestershire sauce
For the cheesy toasts
- 2 keto hot dog buns * See notes
- 1 1/2 cups Gruyere cheese finely shredded
- 4 springs Thyme loosely torn
Instructions
- Preheat the oven to 200C/400F. Line a large baking sheet with parchment paper and set aside.
- Place a large soup pot over medium heat. Once hot, add the butter to melt. Add the sliced onions, sweetener, and pepper, and sauté for 8-10 minutes, until tender and caramelized.
- Add the beef broth and Worcestershire sauce and bring to a simmer. Once it starts simmering, cover the pot and let it simmer for a further 10 minutes.
- While the soup is simmering, prepare the cheesy toasts. Slice your two keto hot dog buns into 6 thick slices, then cut each slice in half. Place the 12 bread pieces on the lined sheet. Sprinkle half the Gruyère cheese over the top. Bake for 6-8 minutes, until golden brown.
- Ladle the soup into small bowls. Add 1-2 pieces of the cheesy toast on top of each soup bowl and sprinkle with extra Gruyere cheese and a sprig of thyme.
This was easy and delicious. I didn’t make a single substitution, except I skipped the buns because I didn’t have any and I don’t like keto buns much. I’ll definitely be making it again this winter. Thanks for the recipe!
Amazing Ann! So glad you enjoyed this one. It’s definitely a great soup to have on hand in the cooler months.
Because no one is ever perfect, I give four stars for your onion soup. French onion soup has always been a favorite of mine, even since I was a young teen. Then I decided to go keto and I had no idea how to or what to cook. I sure thank you for your quick and easy recipes. Way to go and the biggest thing I have to say thank you for? Your recipes are free! Not trying to make a big buck on us internet folk! Now that’s the best news I’ve heard all day.