French Onion Soup with Gruyere Cheese Toasts Recipe

Introduction

French Onion Soup is a comforting classic known for its rich, caramelized onions and savory beef broth topped with melted Gruyere cheese. This hearty soup is perfect for cozy evenings and impresses with its deep, layered flavors.

Ingredients

• 90 g (6 tbsp) unsalted butter
• 1 tbsp oil
• 6 medium yellow/brown onions (about 1.2 kg/2.6 lbs), peeled, halved and thinly sliced
• 1/2 tsp salt
• 1 tsp black pepper
• 3 cloves garlic, minced
• 180 ml (3/4 cup) white wine
• 2 tbsp plain (all-purpose) flour
• 1.5 litres (a splash over 6 cups) good quality strong beef stock
• 1 tbsp Worcestershire sauce
• 1 small baguette, sliced into 2 cm (3/4 inch) slices (about 8 slices)
• 100 g (1 packed cup) grated Gruyere cheese
• Fresh thyme leaves for garnish

Instructions

1. Step 1: Add the butter and oil to a large Dutch oven or heavy-based saucepan and heat over medium-to-low heat until the butter just melts.
2. Step 2: Add the sliced onions, salt, and pepper. Cook uncovered for about 45-50 minutes, stirring occasionally at first and more frequently in the last 15-20 minutes, until the onions are golden brown and caramelized. Adjust heat as needed to prevent burning.
3. Step 3: Stir in the minced garlic and cook for one minute.
4. Step 4: Pour in the white wine to deglaze the pan, scraping up any browned bits. Increase heat to medium-high and cook for 5-8 minutes, stirring often until the wine aroma mostly dissipates.
5. Step 5: Lower the heat to medium and stir in the flour. Cook for one minute while stirring constantly.
6. Step 6: Add the beef stock and Worcestershire sauce. Stir and bring to a boil over medium-high heat.
7. Step 7: Reduce heat to simmer, cover with a lid, and cook for 30 minutes. Taste and add more salt if needed.
8. Step 8: Prepare the cheese baguette slices before the soup finishes cooking.
9. Step 9 (Method 1): Ladle soup into grill-safe bowls, top each with two baguette slices, then sprinkle grated Gruyere over the top. Place bowls under a grill and grill for 2-4 minutes until the cheese melts and bubbles. Carefully remove and sprinkle with fresh thyme leaves before serving.
10. Step 10 (Method 2): Toast baguette slices under the grill until lightly browned, then sprinkle with Gruyere cheese and grill until the cheese melts. Ladle soup into bowls and top each with two cheese toasts. Garnish with fresh thyme leaves and serve.

Tips & Variations

• Use a good quality strong beef stock for rich flavor; homemade or low-sodium store-bought works well.
• Caramelizing the onions slowly is key for deep flavor—don’t rush this step.
• For a vegetarian version, substitute beef stock with mushroom or vegetable stock and omit Worcestershire sauce or use a vegetarian alternative.
• Gruyere cheese is traditional, but Emmental or Swiss cheese can be good substitutes.
• Serve with a side salad or a glass of white wine to complement the meal.

Storage

Store leftover soup in an airtight container in the refrigerator for up to 3 days. Reheat gently on the stove over low heat to avoid burning. Cheese toast toppings are best prepared fresh, but you can keep toasted baguette slices and grated cheese separately and assemble just before serving.

How to Serve

Serve this delicious recipe with your favorite sides.

FAQs

Can I make French Onion Soup ahead of time?

Yes, the soup can be made a day in advance and stored in the refrigerator. Reheat on the stove and add the cheese and bread just before serving for best results.

What bread is best for this soup?

Traditionally, crusty French baguette slices are used because they hold up well when soaked with soup and can be toasted nicely with cheese on top.

French Onion Soup with Gruyere Cheese Toasts Recipe

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★★★★★

4.8 from 111 reviews

This classic French Onion Soup recipe features deeply caramelized onions simmered in a rich beef broth, topped with toasted baguette slices smothered in melted Gruyere cheese and garnished with fresh thyme. Perfectly roasted under the grill to achieve a bubbly, golden cheese crust, this comforting soup combines savory depth and cheesy indulgence for a heartwarming meal.

• Author: Mia
• Prep Time: 15 minutes
• Cook Time: 1 hour 20 minutes
• Total Time: 1 hour 35 minutes
• Yield: 4 servings 1x
• Category: Soup
• Method: Stovetop
• Cuisine: French

Ingredients

Scale 1x2x3x

Sauce Base

• 90 g (6 tbsp) unsalted butter
• 1 tbsp oil
• 6 medium yellow/brown onions (about 1.2 kg/2.6 lbs), peeled, halved and thinly sliced
• 1/2 tsp salt
• 1 tsp black pepper
• 3 cloves minced garlic

Flavour & Thickening

• 180 ml (3/4 cup) white wine
• 2 tbsp plain (all-purpose) flour
• 1.5 litres (a splash over 6 cups) good quality strong beef stock
• 1 tbsp Worcestershire sauce

Toppings

• 1 small baguette, sliced into 2 cm (3/4 inch) slices (we need 8 slices)
• 100 g (1 packed cup) grated Gruyere cheese
• Fresh thyme leaves for garnish

Instructions

1. Prepare the onions: Add the butter and oil to a large Dutch oven or heavy-based saucepan and heat over medium-low heat until the butter has just melted. Add the sliced onions, salt, and pepper.
2. Caramelize the onions: Cook the onions uncovered for about 45-50 minutes. Stir occasionally at first, then frequently during the last 15-20 minutes to avoid burning. The onions should become golden brown and deeply caramelized.
3. Add garlic and cook briefly: Stir in the minced garlic and cook for one minute while stirring.
4. Deglaze with white wine: Pour in the white wine to deglaze the pan, scraping up all browned bits. Increase the heat to medium-high and cook for 5-8 minutes, stirring often, until almost all the wine has evaporated and the aroma subsides.
5. Add flour: Reduce heat to medium and stir in the flour. Cook for one minute, stirring constantly to combine and thicken slightly.
6. Add stock and Worcestershire sauce: Pour in the beef stock and Worcestershire sauce, stir well, then bring the mixture to a boil over medium-high heat.
7. Simmer the soup: Lower heat to a simmer, cover with a lid, and cook for 30 minutes. Taste and adjust salt as needed.
8. Prepare cheese croutons (Method 1): When soup is nearly done, ladle it into grill-safe bowls, top each bowl with two slices of baguette, then sprinkle grated Gruyere evenly on top. Place bowls on a tray and grill for 2-4 minutes until cheese is melted and bubbling. Carefully remove from grill, garnish with fresh thyme, and serve.
9. Prepare cheese croutons (Method 2): Alternatively, toast baguette slices on both sides under the grill until lightly browned. Sprinkle each slice with Gruyere and return to the grill until cheese melts and bubbles. Ladle soup into bowls, place two cheese toasts on top, garnish with thyme, and serve.

Notes

• Use a good quality strong beef stock for the best flavor.
• Watch the onions carefully during caramelization to prevent burning, turning heat down as needed.
• Both methods for melting cheese on the baguette are delicious; choose your preferred way.
• Gruyere melts beautifully and adds authentic flavor, but Swiss cheese is a suitable substitute if needed.
• The soup can be made ahead and reheated gently before adding the cheese topping.

Keywords: French Onion Soup, caramelized onions, beef broth soup, Gruyere cheese soup, classic French soup, comforting soup recipe