Keto French Onion Soup
This keto French onion soup will remind you of the classic bread-topped comfort food – but with far less carbs! By keeping the number of onions in check and topping your soup with a chaffle instead of bread, you end up with all the same flavors and textures in this dish in a way that still fits your keto diet.
If there’s one recipe that my wife loves ordering at restaurants, it’s French onion soup. She gave this dish a big thumbs up, so you know it’s a winner!
How to make keto French onion soup
This low carb soup has three components – the base of the soup, the chaffles for topping, and then the cheese to add on top of that.
Here’s the ingredients you’ll need to make the soup base:
- White wine
- Beef stock
- Bay leaf
All you’ll do is slice up your onions and then sauté them in butter at low heat for a solid 20-30 minutes. Don’t try to rush this process; you want to cook them “low and slow” so it brings out all the natural flavor in the onion. They’ll look like this when you start cooking them…
And then they’ll start to get more golden brown towards the later half of cooking (forgive the bad photos; my kitchen lighting isn’t overly great)…
After that, you’ll add in a little garlic and deglaze the pot with wine. Then add in your stock, bay leaf, and thyme and let it all simmer for about 10-15 minutes.
The total time to make the base does take a while, but as you can see, it’s pretty hands off and only requires minimal ingredients.
While the base of the soup is finishing up, you’ll make the chaffles to go on top. If you haven’t heard of chaffles before, essentially they’re a simple blend of egg and cheese that crisps up amazingly well in a waffle maker!
For this recipe, we used our new Dash waffle maker (<– amazon affiliate link; we earn a commission on qualifying purchases). This is a mini waffle maker that works really well for chaffles. The basic recipe I use frequently is 1/4 cup cheddar, 1/4 cup mozzarella, and 1 egg to make two mini chaffles. You can use those proportions for breakfast waffles, making waffle sandwiches, etc. For this recipe, we’re tripling those basic proportions so we can make 6 mini chaffles – one for each soup serving.
When your soup and chaffles are done, you can transfer the soup to small ramekins and top with the chaffle. Then add about an ounce of shredded gruyere cheese on top, and broil until it’s all melted.
Grab a spoon, dig in, and enjoy!
Helpful recipe tips
- I recommend weighing your onions for the most accuracy with this recipe. I originally planned to use 3-4 onions, but when I weighed them it was far heavier than I expected (which would have pushed the carb count over an ideal amount). I reduced it to two large onions, which ended up weighing a little over a pound (18 ounces). You want to be around 1-1.25 pounds for this recipe, in order to keep the carb count in check. This might look like 2-3 large onions, or 3-4 medium onions, depending on the specific size.
- When you make your chaffles, don’t overfill the mini waffle maker! When we photographed this, I had a helper in the kitchen (ehhhm, my wife) that dumped way too much batter into the mini maker – which causes the batter to drip out all over the sides and make a mess. If you put too much in, you’ll also run out of batter before you’ve got enough chaffles (like we did, haha). We only had enough eggs on hand for one go at the recipe, so you can see that we had to chop our chaffles in half for these photo – as you can see below, haha. 😉
- If you don’t have a mini waffle maker, you can easily make this in a regular Belgian waffle maker too. I would split the batter in half and do two big waffles, and then split each of those into thirds for topping your soup.
- Only make as many chaffles as you need for that evening’s dinner. They don’t hold up as well in the soup for reheating, so it’s best to make them as needed.
Nutrition breakdown for low carb French onion soup
This soup contains 29 grams of fat and 8.9 grams of net carbs per serving. It’s a little higher in net carbs than I might aim for at all meals, but if you’ve got some lower net carb meals at other points in the day – you can easily still stay below 20 grams of net carbs total for the day.
The macronutrient breakdown is as follows:
- 67% fat
- 9% carbs
- 23% protein
In addition to having an acceptable keto meal breakdown, this soup also packs in quite a few vitamins and minerals. Because of the cheese, you’re getting a good helping of your daily calcium needs for bone health. You’ll also get 20% of your daily Vitamin A requirements (for healthy eyesight) and more than 15% of your daily zinc needs (involved in immune health).
Other keto soup recipes
If you’re looking for more keto soup recipes, be sure to check out one of these tasty options from fellow bloggers:
- Instant pot low carb taco soup – 5 g net carbs per serving
- Keto broccoli chicken bacon cheese soup – 4 net carbs per serving
- Lemon oyster mushroom soup – 3 g net carbs per serving
- Jalapeno popper chicken soup – 4 g net carbs per serving
- Keto beef stew – 6.5 g net carbs per serving
I hope you enjoy this keto French onion soup! If you get a chance to try it, we’d love for you to leave a recipe rating or comment below.
Keto French Onion Soup
- 5 tbsp butter
- 2 large onions, sliced*
- 2 tsp minced garlic
- 1/3 cup white wine
- 6 cups beef stock
- 1 bay leaf
- 2 sprigs thyme
For chaffles for topping:*
- 3/4 cup shredded mozzarella
- 3/4 cup shredded cheddar
- 3 eggs
Cheese for topping:
- 6 ounces gruyere, shredded
- Add the butter to a large pot over medium heat. Add the onions and sauté for about 20-30 minutes, stirring frequently, until caramelized.
- Add the garlic and cook for another minute. Pour in the wine and let it simmer for 2 minutes.
- Stir in the beef stock, bay leaf, and thyme. Simmer for about 10-15 minutes.
- While soup is cooking, make your chaffles. Mix together the mozzarella, cheddar, and egg. Spoon out enough batter to just fill a mini waffle maker. Cook until done. Repeat with the remaining batter (this should make about 6 small chaffles).
- Discard the bay leaf and thyme, then ladle your soup into oven safe dishes. Place a chaffle on top of the soup and then add some shredded Gruyere cheese on top of that. Broil for 2-3 minutes until cheese is melted. Enjoy!
- I recommend weighing your onions; you want to aim for around 1-1.25 pounds of onion for this recipe.
- Only make as many chaffles as you need for serving today. For example, if you’re only making two servings today, only use 1/4 cup mozzarella, 1/4 cup cheddar, and one egg. That will make two chaffles.