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–+ servings

Authentic French Onion Soup

This authentic French onion soup is just like one you would find in a quaint restaurant in France. Bubbly, delicious, and topped with browned, stringy cheese… this is a French cooking staple, perfect for a cozy night in or to impress a crowd.
5 from 11 votes
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Prep Time 10 minutes
Cook Time 1 hour 20 minutes
Total Time 1 hour 30 minutes
Servings 6 people
Category Savory

Ingredients
 

For the Soup

  • 8 cups yellow onions, peeled, halved and ¼" sliced (about 2 ½ lbs)
  • 1 Tbsp extra virgin olive oil
  • 3 Tbsp unsalted butter
  • 2 tsp kosher salt (I use Diamond Crystal)
  • ¼ tsp granulated sugar
  • 2 Tbsp all-purpose flour
  • 8 cups low-sodium beef stock (click here for my Homemade Beef Stock recipe)
  • ¾ cup dry white wine (or dry white vermouth)
  • ¼ cup Cognac (or any other variety of brandy)
  • 1 bay leaf, whole
  • ½ tsp ground black pepper

For the Topping

  • 1 French baguette, cut into ¾" rounds
  • 2 cloves of garlic, peeled and halved (for rubbing)
  • 1 ½ cups Gruyère cheese, freshly grated
  • 1 ½ cups Mozzarella cheese, freshly grated
  • ½ cup Parmesan cheese, freshly grated

Instructions

Making the Soup

  • Preheat oven to 325℉.
  • Peel, halve, and slice onions to a ¼" thickness.
    8 cups yellow onions, peeled, halved and ¼" sliced
  • In a large pot, heat olive oil and butter over medium heat.
    1 Tbsp extra virgin olive oil
    3 Tbsp unsalted butter
  • Add in sliced onions. Stir and cover.
  • Cook, stirring occasionally, until onions become soft and translucent (about 15 minutes).
  • Remove cover. Add in sugar, along with 1 tsp of kosher salt.
    ¼ tsp granulated sugar
  • Increase heat slightly and continue to cook onions, uncovered, until rich golden brown in color (about 30 minutes more). Stir occasionally and scrape up any bits on bottom of pan, as needed.
  • Stir in flour. Continue cooking until onions are well coated and flour is cooked (about 2 to 3 minutes).
    2 Tbsp all-purpose flour
  • Add in beef stock, wine, Cognac, bay leaf, pepper, and an additional 1 tsp of kosher salt.
    8 cups low-sodium beef stock
    ¾ cup dry white wine (or dry white vermouth)
    ¼ cup Cognac
    1 bay leaf, whole
    ½ tsp ground black pepper
  • Bring to a boil. Then, reduce heat to medium/low and simmer, partially covered, until all of the flavors have melded together (about 35 minutes).
  • Remove the bay leaf. Taste for seasoning.

Toasting the Baguette Rounds

  • Meanwhile, while the soup is simmering, cut baguette into ¾" rounds and place them on an oven rack or baking sheet. Toast rounds in the oven for 15 minutes.
    1 French baguette, cut into ¾" rounds
  • Remove rounds from the oven. Brush each side of rounds with a raw piece of garlic, which has been peeled and halved.
    2 cloves of garlic, peeled and halved
  • Continue toasting rounds in the oven until they are dry, crisp, and very slightly browned (about 15 minutes more).
  • Remove rounds from the oven and set aside.

Assembling the Soup

  • Turn the oven to a high broil.
  • In a large bowl, mix together Gruyère cheese, Mozzarella cheese, and Parmesan cheese (or whichever combination of cheeses you wish).
    1 ½ cups Gruyère cheese, freshly grated
    1 ½ cups Mozzarella cheese, freshly grated
    ½ cup Parmesan cheese, freshly grated
  • In an oven-safe bowl or tureen, ladle in desired amount of soup. Place one or several toasted baguette rounds on top of soup, and cover generously with a handful of the cheese mixture. Repeat for each serving.
  • Place bowl(s) or tureen(s) on a baking sheet and broil in the oven until the cheese is brown and bubbly (about 5 minutes).
  • Carefully remove from oven. Serve hot.

Notes

  1. When browning the onions (Step 7), you should stir frequently and scrape any bits that stick to the bottom. This ensures that they brown evenly and do not burn. If the onions begin to burn or stick too much you can add in a splash of water and continue to stir.
  2. Alcohol-free version: You can remove the wine and Cognac from this recipe; however, they definitely give the soup an amazing depth of flavor and a more authentic taste.
  3. Best cheese combination: Feel free to use whichever combination of cheeses you like. Gruyère is the traditional cheese used in French onion soup. I have found the above combination of Gruyère, Mozzarella, and Parmesan gives the perfect balance of flavor and stringiness.

Nutrition

Calories: 591kcal | Carbohydrates: 49g | Protein: 29g | Fat: 27g | Saturated Fat: 14g | Polyunsaturated Fat: 2g | Monounsaturated Fat: 8g | Trans Fat: 0.2g | Cholesterol: 70mg | Sodium: 2049mg | Potassium: 1044mg | Fiber: 5g | Sugar: 14g | Vitamin A: 676IU | Vitamin C: 16mg | Calcium: 583mg | Iron: 3mg
Nutrition Disclaimer