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French Onion Soup is a deeply flavorful blend of onions caramelized in butter and slow simmered in a rich medley of beef broth and white wine, then finished with a splash of Cognac and topped with toasted croutons and bubbly Gruyere cheese.

French Onion Soup served in white bowls

I’ve adapted this French Onion Soup recipe from Julia Child’s magnificent book, Mastering the Art of French Cooking. I’ve made a few slight changes: increasing the amount of white wine, reducing the Cognac, adding fresh thyme and topping the soup with toasted squares of crusty bread (aka croutons), less awkward to eat than slices of a standard loaf or baguette. (I did the same in my Vegetarian French Onion Soup recipe.)

It started in Paris

French Onion Soup originated in Paris, France in the early eighteenth century, but I fell in love with it on September 15th, 2001.

It was a Saturday evening and we’d just arrived in Paris with our friends Bryan and Jenn, 6 months pregnant with their first child. Just four days prior we sat together in London, eyes glued to a television screen in horror as we watched images of planes crashing into the World Trade Center. We were, all of us, in Europe for the first time on a long awaited two-week adventure.

Our train arrived in Paris in the late afternoon and by the time we got to our hotel the sky was dark and our stomachs were growling. In the hotel lobby, there were people everywhere. Some were just arriving, like us. Others were in tears, unable to extend their stay with the cities’ hotels at capacity, and unable to fly home as planes were still grounded.

We crossed the street to a restaurant recommended by the hotel concierge. Swirls of cigarette smoke and muffled conversations in an unfamiliar language greeted us. But then steaming bowls of rich French Onion Soup, covered in bubbling cheese were set before us. The soup did not heal the uncertainty or sadness of the situation, but it did taste like comfort and hope.

Food is amazing that way, isn’t it? I especially notice it during the holidays, when we gather with friends and family to enjoy the foods that have become tradition. Somehow they come to represent something more: warmth, safety, gratitude.

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FAQs

What kind of cheese is used in French onion soup?

Gruyere (pronounced “groo-yair”) is the classic Swiss cheese used to top French Onion Soup. If you can find an aged Gruyere, it’s worth the extra cost for its flavor and texture. If you can’t find Gruyere, you could also use Jarlsberg, Emmental or Comté.

What are the best onions for French onion soup?

You can use yellow onions, red onions, sweet onions, or a combination.

How long does it take to make french onion soup?

Give yourself plenty of time to make this soup, properly caramelized onions take time. It’s taken me up to 2 hours, but much of that time is unattended. It is truly an easy process, but the flavor takes time to develop and shouldn’t be rushed.

How to make French Onion Soup

Step 1: Melt butter in a large soup pot; add onion and stir to coat. Cover and cook 15 minutes over low heat.

Cooking onions in butter
Simmering onions in butter on low

Step 2: Meanwhile, toast bread squares until crisp and golden brown. Set aside.

toasting bread cubes

Step 3: Stir salt and sugar into onions and increase heat to medium-low; cook and stir 30 to 4o minutes to caramelize onions to a deep golden brown.

Adding salt and sugar to onions
Cooking onions

Step 4: Add flour; cook and stir 3 minutes.

adding flour to caramelized onions

Step 5: Add thyme. Stir in wine and broth; simmer uncovered 30 to 4 minutes.

adding thyme to caramelized onions
adding wine to caramelized onions
adding broth to caramelized onions

Step 6: Remove from heat and stir in Cognac.

adding cognac to French Onion soup

Step 7: Preheat broiler. Ladle soup into individual, broiler-safe bowls and top each with toasted bread squares and shredded Gruyere cheese. Broil just until cheese is melted and bubbly. Serve.

topping french onion soup with croutons and gruyere cheese
broiling french onion soup

Recipe Video

French Onion Soup

5 from 12 votes
Prep: 15 minutes
Cook: 1 hour 30 minutes
Total: 1 hour 45 minutes
Course: Soup
Cuisine: French
Calories: 317
Servings: 6 people
An easy and authentic French Onion Soup recipe adapted from Julia Child’s famous book, Mastering the Art of French Cooking. 

Ingredients  

  • 3 tablespoons butter salted or unsalted butter
  • 1 1/2 pounds onions thinly sliced (I used yellow onion)
  • 6 ounces crusty bread 1/2-inch thick slices, crusts removed and cut into 1 1/2-inch squares
  • 1 teaspoon fine sea salt
  • 1/4 teaspoon sugar (helps the onions to caramelize)
  • 3 tablespoons all-purpose flour
  • 8 cups beef broth or beef stock
  • 1 cup dry white wine
  • 1 teaspoon fresh thyme leaves from 4 large sprigs or 1/2 teaspoon dried thyme
  • 2 tablespoons Cognac
  • kosher salt and freshly ground black pepper to taste
  • 3 ounces finely grated Gruyère cheese

Instructions 

  • Melt butter in a large pot or Dutch oven over medium heat. Add onion and stir to coat. Reduce heat to low; cover and cook 15 minutes.
  • Meanwhile, make the toasted bread cubes (croutons): Preheat oven to 400°F. 
  • Line a baking sheet with parchment paper and spread bread cubes in a single layer. Bake until crisp and golden brown, 15 to 20 minutes. Remove from oven and set aside.
  • Uncover onions and stir in salt and sugar. Raise heat to medium-low; cook 30 to 40 minutes, stirring often until onions have caramelized to a deep golden brown. Add flour; cook and stir 3 minutes to remove flour taste. 
  • Add thyme, wine and broth to onion mixture and stir, scraping up any browned bits. Increase heat to medium-high and bring to simmer. Reduce heat and let simmer, stirring occasionally, 30 to 40 minutes to your desired taste and consistency. Remove from heat and stir in Cognac. Add salt and pepper to taste
  • Preheat broiler.
  • Ladle soup into 6 individual broiler-safe bowls. Top each bowl with 1/6 each of the toasted bread cubes and shredded cheese.  Arrange bowls on a baking sheet and place under broiler. Broil until cheese is melted and bubbly. Serve.

Notes

If you don’t want 6 servings of this soup at once, no problem! Make the full recipe of onion soup, but prepare just enough bread and cheese for the number of servings you want. Then reheat the leftover soup as needed, finishing with bread and cheese.

Nutrition

Calories: 317kcal | Carbohydrates: 30g | Protein: 12g | Fat: 11g | Saturated Fat: 6g | Cholesterol: 30mg | Sodium: 1827mg | Potassium: 414mg | Fiber: 2g | Sugar: 6g | Vitamin A: 325IU | Vitamin C: 8.9mg | Calcium: 206mg | Iron: 2.2mg

Nutrition information is automatically calculated, so should only be used as an approximation.

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45 Comments

  1. Cinda says:

    Are there substitutes to use if you’d rather not use the alcohol?

    1. Marissa Stevens says:

      Hi Cinda! Absolutely. Just replace the cup of white wine with either more beef broth or chicken broth if you have it on hand (the mix is great, as in Pasta e Fagioli) and omit the cognac.

  2. Claire says:

    5 stars
    Ever since my first bowl of traditional French onion soup in France I have searched for a recipe to repeat the experience at home. Thank you so much for this easy to follow delicious recipe. I substituted Jack Daniels for the cognac and added a touch of goats cheese with some Jarlsberg at the end. Are use the bone marrow broth and it all paid off. I am sure I will be using this recipe again and again. Five bright shining stars!

    1. Marissa says:

      Claire, I’m so glad that you enjoyed this and that you made it your own! I bet that bone marrow broth made it wonderfully rich and flavorful!

  3. Bridget Varney says:

    5 stars
    This is wonderful, I substituted good whiskey for the cognac and it was amazing.

    1. Marissa says:

      That’s fantastic, Bridget! So glad you enjoyed it!!

  4. Pat says:

    5 stars
    This came out so good! . Such a clever idea with the croutons.
    Thanks for a wonderful recipe.

    1. Marissa says:

      Thank you very much, Pat! I’m so glad you enjoyed it!