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closeup of a spoonful of French onion soup with a crouton and melted cheese
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5 from 4 votes

Soupe à l'Oignon Gratinée (Parisian French Onion Soup)

This traditional French Onion Soup (Soupe à l'Oignon Gratinée) recipe comes directly from Paris! It's a recreation of the classic served at Au Père Louis, a beloved Parisian bistro in Le Quartier Latin, or Latin Quarter, known to have some of the best French onion soup in Paris.
Prep Time25 mins
Cook Time1 hr 20 mins
Total Time1 hr 45 mins
Course: Main Course, Soup
Cuisine: French
Servings: 4 servings
Calories: 609kcal
Author: Victoria

Ingredients

  • 2 tablespoons vegetable oil
  • 2 ½ pounds yellow onions peeled and sliced into ¼-inch thick half-moons
  • 1 teaspoon kosher salt plus more as needed
  • 4 cloves garlic thinly sliced lengthwise
  • 2 bay leaves
  • 1 tablespoon flour
  • 2 tablespoons Madeira or port wine
  • 6 cups beef broth or stock heated
  • Freshly ground black pepper
  • 4 cups (5 ½ to 6 ounces) cubed crusty baguette (¾-to-1-inch cubes)
  • 1 tablespoon olive oil or olive oil spray
  • 8 to 12 ounces Gruyère cheese grated

Instructions

  • Heat oil in a large pot over medium-high heat. Add the onions and salt and toss to coat evenly with the oil. Lower the heat to medium-low, cover and cook, stirring occasionally, sweating the onions until they are softened, about 15 minutes.
  • Remove the lid and continue to cook uncovered, stirring occasionally another 15 to 20 minutes until most of the residual moisture has evaporated, but don’t cook long enough to caramelize. Add the garlic and bay leaves and cook for another 3 minutes until fragrant.
  • Stir in the flour and then the port wine. Add the hot beef broth and stir to combine. Season with more salt and pepper. Partially cover with a lid and simmer on low for about 45 minutes, stirring occasionally, skimming impurities, and adjusting seasoning as needed (don’t be stingy on the pepper!).
  • Meanwhile, preheat the oven or toaster oven to 375°F. Toss the bread cubes with the olive oil or spray them with olive oil spray, and toast in the oven for about 15 to 20 minutes until golden and crusty. Set aside.
  • Turn on the broiler. Divide the soup into 4 oven-proof bowls, top with the croutons (about 1 cup per serving), and then finish with 2 to 3 ounces of grated Gruyère per serving. Make sure to evenly cover all the croutons with cheese or else the croutons could burn a little when you broil. Broil until cheese is melted, bubbly, and golden.

Notes

  • Cooked French onion soup can be refrigerated for 3 to 4 days or frozen in airtight containers for 4 to 6 months. I also like to freeze portions of baguette in freezer bags (because you don't use an entire baguette for this recipe so there is always extra) and then thaw them to make croutons when I am ready to enjoy another batch of this soup!
  • Cubed baguette is really essential here to get the perfect croutons for your soup. I have tried making croutons for this soup with other crusty breads, but the ratio of crust to soft bready interior is best with a baguette because it has so much more crust. Every single crouton should have a bit of crust on it for optimal texture. I may sound nitpicky but TRUST me I've been making French onion soup for decades and this is the best way to do it. I usually cut each slice of baguette in half and then into thirds and they are the perfect size cubes with the perfect amount of crust.
  • I have made this soup with homemade stock (recipe follows) and with beef broth concentrate. I obviously love the soup made with my homemade stock, however the soup is still excellent and flavorful with the beef broth concentrate. In a pinch store-bought broth is fine, but for a truly authentic experience aim to make your own stock if you have the time to. I’ve also tried it with equal parts beef broth and chicken broth, and it's still hearty and delicious.
  • You can omit the flour entirely if you prefer a thinner broth, or increase to 2 tablespoons if you’d like a thicker broth, but I think the 1 tablespoon is optimal.
  • For the port or Madeira wine, I have made this recipe with both 2 and 4 tablespoons, and prefer the lesser amount, but both are delicious so feel free to add more if you prefer a sweeter onion soup!
  • Inspired by my visit to Au Père Louis in Paris

Nutrition

Calories: 609kcal | Carbohydrates: 53g | Protein: 23g | Fat: 29g | Saturated Fat: 11g | Polyunsaturated Fat: 5g | Monounsaturated Fat: 4g | Cholesterol: 62mg | Sodium: 1974mg | Potassium: 66mg | Fiber: 6g | Sugar: 22g