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French Onion Soup

French onion soup with slow-caramelized onions and a rich beef broth, finished with toasted baguette and a golden Gruyère cheese crust. Cook the onions until deeply golden and jammy, then broil until the cheese is melted and bubbling.
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Prep Time 15 minutes
Cook Time 1 hour 30 minutes
Total Time 1 hour 45 minutes
Servings: 6 servings
Course: Main Dish
Cuisine: French
Calories: 560
Ingredients Equipment Method Notes

Ingredients
  

Yellow onions, thinly sliced
  • 4 lb yellow onions Thinly sliced for even caramelization.
Fat for caramelizing
  • 4 tbsp unsalted butter
  • 1 tbsp olive oil
Wine for deglazing
  • 1 cup dry white wine or sherry Use dry wine or sherry for best flavor.
Soup base
  • 6 cup beef broth
  • 2 sprigs fresh thyme
  • 1 bay leaf bay leaf
  • 1 tsp Worcestershire sauce
Bread topping
  • 6 baguette or French bread slices, toasted Toast until just golden before broiling.
Cheese topping
  • 2 cup Gruyere cheese, shredded
  • 0.5 cup parmesan, grated
Seasoning
  • 1 salt and pepper to taste Season throughout and at the end.

Equipment

  • 1 Dutch oven

Method
 

Caramelize the onions
  1. Melt the butter with the olive oil in a large heavy pot over medium heat, then add the onions and 1/2 teaspoon salt. Stir to coat and distribute the salt evenly.
  2. Cook the onions for 60-70 minutes over medium heat, stirring every 10-15 minutes, until deeply golden, jammy, and caramelized. Use the frequent stirring to prevent scorching and build a deep brown color.
Build the broth
  1. Deglaze with the wine (or sherry) and cook for 3 minutes, scraping up all browned bits from the pot. Reduce slightly so the raw wine taste cooks off.
  2. Add the beef broth, thyme, bay leaf, and Worcestershire sauce, then simmer for 20 minutes. Skim lightly if needed and keep a gentle simmer.
  3. Remove the thyme and bay leaf, then season the soup with salt and pepper to taste. Taste after removing the aromatics and adjust before serving.
Assemble and broil
  1. Ladle the hot soup into oven-safe crocks, then float the toasted baguette slices on top. Make sure the bread sits in contact with the broth for soft edges.
  2. Pile the Gruyère and parmesan over the bread, then broil for 3-4 minutes until melted and bubbly. Look for a golden-brown, blistered cheese surface before serving.

Notes

Pro tip: caramelize the onions patiently—consistent stirring every 10-15 minutes helps you reach a jammy, dark golden color without burning. Store leftovers covered in the refrigerator up to 3 days; reheat gently on the stovetop and add fresh bread + cheese if you want the best crust. Freezing is not recommended for the assembled, cheese-topped soup, but the onion broth base can be frozen up to 3 months. For a lighter option, use reduced-sodium beef broth and reduce the parmesan by 1/4 cup.