Classic French Onion Soup is a comforting and flavorful dish made with caramelized onions, a savory broth, and topped with toasted cheesy bread. This iconic soup is easy to make and perfect for a cozy dinner or an impressive appetizer. Vegetarian and gluten-free adaptations make this recipe versatile for any dietary preferences.

Why You’ll Love This Recipe

Rich and Flavorful: Slow-cooked onions and a robust broth create deep, complex flavors.
Restaurant-Quality: Feel like a chef in your own kitchen with this gourmet classic.
Customizable: Easy to adapt for vegetarian or gluten-free diets.
Budget-Friendly: Uses simple, inexpensive ingredients for an elegant result.

Ingredients

(Tip: You can find the complete list of ingredients and their measurements in the recipe card below.)

For the Soup

3 lbs onions, thinly sliced
4 tablespoons butter (unsalted or salted)
1 tablespoon olive oil or vegetable oil
¾ teaspoon kosher or sea salt
¼ teaspoon black pepper, freshly ground
2 tablespoons all-purpose flour (use gluten-free flour for GF adaptation)
8 cups beef broth or beef stock (substitute with vegetable broth for vegetarian)
¾ cup dry white wine
1 tablespoon dry sherry (optional)
½ teaspoon Worcestershire sauce
1 bay leaf
2 sprigs fresh thyme

For the Topping

1 small baguette, sliced into rounds
6 oz Gruyere cheese, shredded

Directions

1. Caramelize the Onions

Heat butter and olive oil in a large pot over medium heat.
Add the sliced onions, salt, and pepper. Cook for 35–40 minutes, stirring occasionally, until the onions are deeply golden and caramelized. Reduce the heat slightly if the onions start to burn.

2. Add the Flour

Sprinkle the flour over the onions and stir well. Cook for 1–2 minutes to remove the raw flour taste.

3. Deglaze the Pot

Pour in the white wine and dry sherry (if using). Stir to scrape up any browned bits from the bottom of the pot. Simmer for 2–3 minutes.

4. Add the Broth and Simmer

Stir in the beef broth, Worcestershire sauce, bay leaf, and thyme. Bring to a boil, then reduce the heat and simmer uncovered for 30–40 minutes. Discard the bay leaf and thyme sprigs before serving.

5. Prepare the Topping

Preheat your oven broiler. Arrange baguette slices on a baking sheet and toast under the broiler until golden brown on both sides.
Top each slice with shredded Gruyere cheese and return to the broiler until the cheese is melted and bubbly.

6. Assemble and Serve

Ladle the soup into oven-safe bowls. Place the toasted cheesy bread on top of each bowl.
Optional: Place the bowls under the broiler for 1–2 minutes to further melt and brown the cheese. Serve hot.

Servings and Timing

Yield: 4 servings
Prep Time: 15 minutes
Cook Time: 1 hour 35 minutes
Total Time: 1 hour 50 minutes

Variations

Vegetarian Version: Use vegetable broth and omit Worcestershire sauce.
Gluten-Free Option: Use gluten-free flour and serve with GF bread.
Cheese Alternatives: Substitute Gruyere with Swiss, Emmental, or a mild cheddar.
Alcohol-Free: Omit wine and sherry; add an extra ½ cup of broth for liquid balance.
Herbal Notes: Add a sprig of rosemary or a pinch of herbes de Provence for additional aroma.

Storage/Reheating

Storage: Store soup (without the bread topping) in an airtight container in the refrigerator for up to 3 days.
Reheating: Reheat gently on the stovetop or in the microwave until hot. Add fresh bread and cheese before serving.
Freezing: Freeze the soup (without the bread) for up to 2 months. Thaw overnight in the refrigerator before reheating.

FAQs

1. Can I use red onions instead of yellow?

Yes, red onions work but will have a slightly sweeter and milder flavor.

2. What’s the best way to slice onions for this recipe?

Slice them thinly and evenly for consistent caramelization.

3. Can I make this soup ahead of time?

Yes, the flavors deepen when made ahead. Reheat and add the bread and cheese just before serving.

4. What type of wine works best?

Dry white wines like Sauvignon Blanc or Chardonnay are ideal.

5. Can I substitute Worcestershire sauce?

Use soy sauce or tamari (for gluten-free) as a substitute.

6. How do I prevent the onions from burning?

Cook over medium heat, stir occasionally, and reduce the heat if they start to darken too quickly.

7. What type of bread is best?

A crusty baguette works best for the topping.

8. Can I use pre-shredded cheese?

Pre-shredded cheese can work, but freshly shredded cheese melts better and tastes fresher.

9. Can I skip the broiling step?

Yes, but broiling gives the cheese a delicious bubbly and golden finish.

10. How do I know the onions are properly caramelized?

They should be golden brown, soft, and have a sweet, jam-like consistency.

Conclusion

Classic French Onion Soup is a timeless recipe that brings rich flavors and a comforting warmth to your table. With its deeply caramelized onions, savory broth, and cheesy bread topping, it’s a dish that feels both indulgent and rustic. Perfect for a cozy night in or as an elegant appetizer, this recipe is sure to impress. Try it today and enjoy the satisfying flavors of this French classic!