French onion soup is the ultimate comfort food, but traditional recipes are loaded with carbs from bread. This Keto French Onion Soup lets you enjoy all the rich flavors of the original—sweet caramelized onions, savory beef broth, and melted gruyère cheese—without the guilt. With just a few smart swaps, you can make this classic low-carb, high-fat, and keto-approved, perfect for weight loss or a cozy night in.
History of French Onion Soup
French Onion Soup (Soupe à l’Oignon) is one of France’s most beloved and enduring culinary traditions. This rich, savory soup has roots dating back to ancient Rome, where onion-based broths were commonly made due to onions being affordable and easy to store. However, the dish as we know it today was perfected in 18th-century France and became a hallmark of Parisian cuisine.
One of the most popular legends attributes the modern French onion soup to King Louis XV. As the story goes, the king found himself at a hunting lodge late one night with only onions, butter, and champagne in his pantry. He combined them to create the first version of the soup. Another story credits Duke of Lorraine, Stanislas Leszczyński, who, upon tasting the soup at a roadside inn, fell in love with it and helped popularize it among the French nobility.
During the 19th century, French onion soup became a staple of Les Halles, Paris’ famous central market, where working-class vendors and late-night revelers would enjoy it as a warm, filling dish after long shifts. The soup was often served in taverns and bistros, eventually becoming a favorite across France.
Keto-Friendly Bread Options: Serve with 90-second keto bread, almond flour toast, or parmesan crisps.
The Best Low-Carb French Onion Soup Recipe – Guilt-Free Indulgence
Description
Caramelized onions simmered in a savory beef broth, topped with gooey melted cheese. This keto-friendly version swaps traditional carb-heavy bread with crispy keto croutons or cheese crisps for a guilt-free indulgence.
Ingredients:
For the Soup:
4 large yellow onions, thinly sliced
3 tbsp butter
2 tbsp olive oil
4 cups beef broth (preferably homemade or low-sodium)
1/2 cup dry white wine (optional but enhances flavor)
1 tsp Worcestershire sauce
1 tsp fresh thyme leaves (or ½ tsp dried)
2 cloves garlic, minced
1/2 tsp sea salt (adjust to taste)
1/2 tsp black pepper
1/2 tsp onion powder (boosts flavor)
For the Topping:
1 cup gruyère cheese, shredded
1/2 cup parmesan cheese, grated
Keto-friendly bread slices or cheese crisps for serving
Instructions:
Caramelize the Onions – In a large pot, heat butter and olive oil over medium-low heat. Add onions and slowly cook for 30-40 minutes, stirring occasionally, until they turn deep golden brown.
Deglaze the Pot – Pour in white wine and scrape up any browned bits from the bottom. Let it simmer for 2 minutes until the wine reduces slightly.
Add Broth & Seasonings – Stir in the beef broth, Worcestershire sauce, thyme, garlic, salt, and pepper. Simmer on low heat for 20 minutes, allowing the flavors to blend.
Prepare the Topping – Preheat your oven’s broiler. Ladle soup into oven-safe bowls. Top each with keto bread croutons or cheese crisps, then sprinkle generously with gruyère and parmesan.
Broil to Perfection – Place under the broiler for 2-3 minutes, or until the cheese is melted and bubbly.
Serve & Enjoy – Let cool slightly before enjoying this rich, cheesy, and savory keto delight!
Meal Prep & Serving Suggestions:
Make-Ahead: Store in an airtight container in the fridge for up to 4 days.
Freezing: Freeze the soup without the cheese topping for up to 3 months.
Keto-Friendly Bread Options: Serve with 90-second keto bread, almond flour toast, or parmesan crisps.
Pair It With: A green salad with olive oil dressing for a balanced keto meal.
Estimated Cost: $10-$15 for 4 servings
Nutritional Values (Per Serving):
Calories: ~320
Fat: ~25g
Protein: ~12g
Net Carbs: ~5g
