Keto French Onion Soup (The Real Secret Recipe)

Onions run higher in carbs, that part is true, but this technique for coaxing out maximum flavor lets you use fewer onions and still get all the flavor. Keto French onion soup is the same recipe I have made since my days as a private chef, long before I owned my own restaurant.

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The real secret is a combination of beef and chicken broth together, plus genuine patience while the onions caramelize.

Chef Jenn’s Take on French Onion Soup

The real secret is combining both beef and chicken broth together. All beef overwhelms the delicate onion flavor, and all chicken does not give the soup enough body, but the two together genuinely balance out.

Melt the butter until sizzling but not browned, add the sliced onions, and turn the heat down to medium-low. Cook slowly, stirring frequently, for about 30 minutes or a bit longer, until dark golden brown, moist and creamy, not crunchy or dried out. Low heat and real patience get you there, do not rush it. Add the garlic for the last minute. Deglaze with red wine if you want, or a bit of broth, then everything goes into the soup pot to simmer covered for 20 minutes.

Do not add the chaffle or bread topping until the very last minute, or it turns soggy fast. Use shredded cheese, not sliced, for the best melting.

Use regular yellow onions specifically, not Spanish or sweet onions, which run higher in sugar and carbs. You can make this vegetarian too, swap in vegetable broth for both the beef and chicken broth. One reader tried it and loved it.

What You’ll Love About French Onion Soup

• That golden, bubbly cheese topping makes it feel like a real occasion.
• A rich, deeply flavored broth built on a genuine chef technique.
• Fewer onions and full flavor, thanks to the combined broths.

Ingredients

• Yellow onions – Regular yellow onions specifically, sliced. Skip Spanish or sweet onions, which run higher in sugar.
• Garlic – Fresh, minced.
• Butter – Salted.
• Red wine – Optional, for deglazing.
• Chicken broth – Low or no sodium, or use homemade Chicken Bone Broth.
• Beef broth – Low or no sodium.
• Bay leaves – Whole, removed before serving.
• Fresh thyme – Dried thyme works too, in a smaller amount.
• Cheese – Gruyere for a classic flavor, or use what you have. Shredded melts best.

How to Make French Onion Soup

Scroll down for the full recipe card with exact measurements and printable instructions.

Melt the butter in a skillet large enough to hold the onions, over medium heat. Add the sliced onions and turn the heat down to medium-low. Cook slowly, stirring frequently, until dark golden brown and soft, about 30 minutes.

Add the garlic and cook 1 more minute. Set aside. Deglaze the skillet with the red wine, letting it simmer for 2 minutes, or deglaze with 1/2 cup of the broth instead. Scrape everything into a soup pot.

Add the onions, thyme, bay leaves, and remaining broth to the soup pot. Cover and simmer for 20 minutes.

Remove the thyme sprigs and bay leaves, and season with salt and pepper.

Ladle into oven-safe bowls and top with a chaffle or low-carb bread and shredded cheese. Broil until hot and bubbly.

Make It A Meal

I love a fresh salad topped with Ranch Dressing alongside a bowl of this, or if I’m especially hungry, toasty Sourdough Chaffles on the side.

For more soups, Broccoli Cheese Soup and Chicken Zoodle Soup are both worth adding to the rotation.

Storage

This freezes beautifully. Chill it thoroughly, then package in freezer-safe containers for up to 3 months. Thaw and reheat on the stovetop or in the microwave, then add the fresh cheese and bread or chaffle topping right before serving.

Frequently Asked Questions