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Classic French onion soup topped with toasted baguette slices and melted Gruyère cheese in an oven-safe soup crock.

Classic French Onion Soup

This classic French onion soup is rich, savory, and loaded with deeply caramelized onions simmered in beef broth and dry sherry. Finished with toasted baguette slices and melted Gruyère and Parmesan cheeses, it’s a cozy restaurant-style soup made right at home.
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Prep Time 15 minutes
Cook Time 1 hour 15 minutes
Total Time 1 hour 30 minutes
Servings: 6
Course: Soup
Cuisine: French
Ingredients Method Notes

Ingredients
  

  • 3 pounds yellow onions about 5–6 large, thinly sliced
  • 4 tablespoons unsalted butter
  • 1 tablespoon olive oil
  • 1 teaspoon kosher salt plus more to taste
  • ½ teaspoon black pepper
  • 2 cloves garlic minced
  • 1 tablespoon fresh thyme leaves or 1 teaspoon dried
  • ½ cup dry white wine or dry sherry
  • 6 cups high-quality low-sodium beef stock
  • 1 teaspoon Worcestershire sauce
1 bay leaf
  • 1 baguette sliced into ½-inch rounds
  • 1½ cups freshly grated Gruyère cheese
  • ½ cup grated Parmesan cheese

Method
 

Caramelize the onions
  1. In a large Dutch oven over medium heat, melt butter with olive oil.
Add onions, salt, and pepper.
  2. Cook, stirring every few minutes, for 45–60 minutes until deeply golden and jam-like.
Lower heat if needed to prevent burning. If onions begin sticking too aggressively, add a splash of water and continue cooking.
Build the broth
  1. Stir in garlic and thyme. Cook 1 minute.
  2. Add wine or sherry and scrape up browned bits. Simmer until almost completely reduced.
  3. Add beef stock, Worcestershire, and bay leaf.
Bring to a gentle simmer and cook uncovered 25–30 minutes.
  4. Remove bay leaf. Adjust salt and pepper.
Toast the bread
  1. Preheat oven to 400°F.
Toast baguette slices until lightly crisp on both sides.
Assemble and broil
  1. Ladle soup into oven-safe bowls.
Top each with toasted bread.
Cover generously with Gruyère and a sprinkle of Parmesan.
  2. Broil 2–4 minutes until melted and bubbling with browned edges.
  3. Serve immediately.

Notes

  • Proper caramelization is the key. The onions should be deep amber, not pale gold.
  • Use low-sodium stock and adjust seasoning at the end.
  • For freezing, store soup without bread or cheese. Add fresh toppings when serving.
  • Rest 5 minutes after broiling before serving — cheese sets slightly and flavors deepen.