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Authentic French Onion Soup

This classic French onion soup features caramelized onions, rich beef broth, and a decadent cheese topping. It's the perfect comfort food for a cozy evening.
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Prep Time 15 minutes
Cook Time 45 minutes
Total Time 1 hour
Course Soup
Cuisine French
Servings 4 People
Calories 350 kcal

Equipment

  • 1 large saucepan or Dutch oven
  • 1 wooden spoon
  • 1 ladle
  • 1 broiler-safe soup bowls

Ingredients
  

  • 4 large onions, thinly sliced About 1.5 kg.
  • 4 tablespoons unsalted butter
  • 2 tablespoons olive oil
  • 1 teaspoon sugar
  • 1 teaspoon salt
  • ½ teaspoon freshly ground black pepper
  • 4 cups beef broth About 1 liter.
  • 1 cup dry white wine About 240 ml.
  • 1 tablespoon all-purpose flour
  • 1 teaspoon dried thyme Or 1 tablespoon fresh thyme.
  • 8 slices baguette or crusty bread
  • 1 ½ cups Gruyère cheese, shredded About 150 grams.
  • to taste fresh parsley, for garnish Optional.

Instructions
 

  • In a large saucepan or Dutch oven, melt the butter and olive oil over medium heat.
  • Add the sliced onions, salt, and sugar. Cook, stirring frequently, for about 30-35 minutes until the onions are deeply caramelized and golden brown.
  • Sprinkle the flour over the caramelized onions and stir until well combined, cooking for an additional 1-2 minutes.
  • Pour in the white wine, scraping the bottom of the pan to deglaze and incorporate any browned bits. Allow to simmer for 5 minutes to reduce by half.
  • Add the beef broth and thyme, bringing the mixture to a boil. Reduce heat to low and let it simmer for about 10 minutes.
  • While the soup simmers, preheat the broiler. Toast the slices of baguette until golden brown on both sides.
  • Ladle the soup into broiler-safe bowls. Place a toasted slice of baguette on top of each bowl, and generously sprinkle with shredded Gruyère cheese.
  • Place the bowls under the broiler for 2-3 minutes, or until the cheese is bubbly and golden brown.
  • Carefully remove the bowls from the oven and let them cool slightly. Garnish with fresh parsley if desired, and serve hot.

Notes

For a deeper flavor, consider using a combination of beef and chicken broth.
This soup can be made a day in advance; simply reheat before serving and add the bread and cheese just prior to broiling.
Adjust the amount of cheese based on personal preference for a thicker topping.