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Keto French Onion Soup

A low-carb version of the classic French onion soup with caramelized onions, rich broth, and melted cheese topping using keto-friendly bread alternatives.
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Prep Time 15 minutes
Cook Time 45 minutes
Servings: 6
Calories: 320
Ingredients Method Notes

Ingredients
  

For the Soup
  • 4 large yellow onions, thinly sliced
  • 3 tablespoons butter
  • 2 tablespoons olive oil
  • 1 teaspoon salt
  • 6 cups beef broth (low-sodium preferred)
  • ½ cup dry white wine (optional)
  • 2 bay leaves
  • 1 teaspoon fresh thyme
  • ½ teaspoon black pepper
For the Topping
  • 1½ cups shredded Gruyère cheese
  • ½ cup grated Parmesan cheese
  • 6 slices low-carb bread or cheese crisps

Method
 

  1. Heat butter and olive oil in a large, heavy-bottomed pot over medium heat. Add sliced onions and salt, stirring to coat evenly. Cook for 25-30 minutes, stirring occasionally, until onions turn deep golden brown and develop a sweet, jammy consistency.
  2. Add white wine (if using) to deglaze the pot, scraping up any brown bits from the bottom. Let wine reduce for 2 minutes until alcohol cooks off. Pour in beef broth, add bay leaves, thyme, and black pepper.
  3. Bring to a gentle boil, then reduce heat and simmer for 15 minutes. Remove bay leaves and taste for seasoning – adjust salt and pepper as needed.
  4. Preheat broiler. Ladle the hot soup into oven-safe bowls, filling them about ¾ full.
  5. Place one slice of low-carb bread or a few cheese crisps on top of each soup bowl. Generously sprinkle mixed Gruyère and Parmesan cheese over the bread. Place bowls on a baking sheet.
  6. Broil for 2-4 minutes until cheese is bubbly, golden, and slightly crispy around edges. Watch carefully to prevent burning. Serve immediately while cheese is still bubbling.

Notes

Caramelize onions up to 3 days in advance and store refrigerated to improve flavor. Use oven-safe bowls for broiling. Watch carefully during broiling to prevent burning. Soup base can be refrigerated for up to 4 days or frozen for up to 3 months without cheese topping.