This Low-Carb French Onion Soup Will Ruin All Other Soups For You Forever!

French onion soup has always been a classic comfort dish, but when you’re following a keto lifestyle, sometimes you need to make a few tweaks to keep it low-carb.

That’s where this Keto French Onion Soup comes in—deliciously rich, savory, and every bit as satisfying as the original.

The magic lies in the combination of caramelized onions, rich beef stock, and aromatic herbs; all finished off with a layer of melted Swiss or Gruyere cheese. The soup itself is so flavorful you won’t even miss the bread traditionally used to top it.

For that classic topping, I’ve created a simple keto dough that mimics the crispy, bubbly topping you’d expect from the best French onion soups without the carbs!

Not only does this soup taste like a restaurant-quality dish, but it’s also a great option for meal prepping.

Why I Love This Recipe?

• Comforting and Cozy: The rich, hearty broth and melted cheese are the ultimate comfort food—perfect for chilly evenings.
• Low-Carb Goodness: You get all the flavor of French onion soup without the carbs, so you can stay on track with your keto goals.
• Customizable: Swap the beef stock for vegetable stock to make it vegetarian-friendly, or add extra protein like shredded chicken.
• A True Showstopper: The keto dough topping gives this soup that authentic feel, with all the crispiness you love—minus the carbs!
• Perfect for Meal Prep: Make a big batch to enjoy throughout the week or share with friends—it keeps and reheats wonderfully.

Keto French Onion Soup Recipe

A rich, savory French onion soup with caramelized onions, aromatic herbs, and a hint of sweetness. Topped with golden thyme croutons and melty Swiss cheese, it’s pure comfort in a bowl.

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Prep Time 20 minutes mins

Cook Time 1 hour hr 10 minutes mins

Total Time 1 hour hr 30 minutes mins

Course Soup

Cuisine French

Servings 8

Calories 418 kcal

Equipment

• Large saucepan
• Wooden spoon or spatula
• Knife and chopping board
• Measuring cups and spoons
• Baking sheet
• Parchment paper
• Oven
• Ladle
• Oven-proof bowls
• Broiler

Ingredients

  

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 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

Instructions

 

For the Soup:

• Heat olive oil and butter in a large saucepan over low-medium heat.
• Add onions, salt, and pepper; cook uncovered for 30 minutes until golden brown.
  
• Stir in garlic; cook for 2–3 minutes. Add white wine, thyme, and bay leaves; cook for 5 minutes.
  
• Pour in water, stock, Worcestershire sauce, and erythritol. Simmer uncovered for 30 minutes.
  
• Remove bay leaves, taste, and adjust seasoning. Keep warm or store for later use.
  

For the Toppers:

• Preheat oven to 375°F. Divide dough into 8 balls, press into discs, and place on a parchment-lined baking sheet.
  
• Press thyme leaves or sprigs into each disc and bake for 15 minutes until golden. Cool and store if needed.

To Assemble and Serve:

• Heat the soup, ladle into oven-proof bowls, and top with a thyme crouton and cheese slice.
  
• Broil for 2–3 minutes until the cheese melts and turns golden. Serve hot.

Nutritional Info:

Tips that Will Help You Out!

• Caramelizing the Onions: Take your time with caramelizing the onions, as the slow cooking process brings out their natural sweetness, a key flavor in this soup.
• Wine Alternative: If you prefer to skip the wine, you can use extra broth or a splash of apple cider vinegar for a bit of acidity.
• Keto Dough: Make sure your keto dough is pressed into even discs to ensure uniform cooking and a perfect texture for your croutons.
• Cheese Options: If you prefer a different cheese, Gruyere or mozzarella are great options for melting. Gruyere, however, provides that authentic French onion soup taste.
• Worcestershire Sauce Tip: Use a gluten-free Worcestershire sauce if you’re following a gluten-free diet. You can also use tamari sauce as a soy-based alternative.

Joe Miller

Joe Miller is the passionate founder of Food Landscape Insight, where he shares his love for cooking and culinary experiences. Growing up in a family-run diner, Joe was immersed in the vibrant world of food from an early age. The kitchen became his canvas, and food, his way of storytelling.

Through years of experimentation and learning, Joe honed his skills and started his blog to inspire others to embrace the joy of cooking. Each recipe he shares is a blend of tradition, creativity, and the heartfelt memories that food brings to life, all with the aim of fostering a deeper connection to food.