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French Onion Soup

French onion soup with slow-caramelized onions and a rich broth, finished with a melty Gruyère and parmesan cheese crust on toasted baguette. Classic French method: reduce onions until deeply golden and jammy, then simmer with thyme, bay, and Worcestershire for depth.
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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: 610
Ingredients Equipment Method Notes

Ingredients
  

Onions
  • 4 lb yellow onions Thinly sliced for faster caramelization.
Fats for caramelizing
  • 4 tbsp unsalted butter Helps onions turn deeply golden.
  • 1 tbsp olive oil Prevents butter from browning too quickly.
Seasoning and aromatics
  • 1 tsp Worcestershire sauce Adds savory depth to the broth.
  • 0.5 bay leaf Use whole sprig/leaf; remove after simmering.
  • 2 sprig fresh thyme Remove thyme sprigs after simmering.
Wine for deglazing
  • 1 cup dry white wine or sherry Scrapes up browned bits from the pot.
Broth base
  • 6 cup beef broth Simmer to develop a flavorful onion broth.
Bread topping
  • 6 baguette or French bread Slice and toast; float on top of crocks.
Cheese topping
  • 2 cup Gruyere cheese Shred and pile over the bread.
  • 0.5 cup parmesan Grate and add alongside Gruyère for extra browning.
To taste
  • Salt and pepper to taste Use to season onions and final broth as needed.

Equipment

  • 1 Dutch oven

Method
 

Caramelize the onions
  1. Melt butter with olive oil in a large heavy pot over medium heat, then add onions and 1/2 teaspoon salt.
  2. Cook onions 60-70 minutes, stirring every 10-15 minutes, until deeply golden, jammy, and caramelized.
Build the broth
  1. Pour in the white wine or sherry and cook for 3 minutes, scraping up all browned bits.
  2. Add beef broth, thyme, bay leaf, and Worcestershire, then simmer for 20 minutes.
  3. Remove thyme and bay leaf, then season the broth with salt and pepper to taste.
Broil the cheese crust
  1. Ladle soup into oven-safe crocks, then float toasted baguette slices on top.
  2. Pile Gruyère and parmesan over the bread, then broil for 3-4 minutes until melted and bubbly and visibly golden at the edges.

Notes

For best flavor, don’t rush caramelization—60-70 minutes of steady stirring is what turns the onions jammy and sweet. Refrigerate leftovers in sealed containers up to 3 days; rewarm gently on the stovetop and broil the cheese topping to re-melt. Freezing is not recommended because the onion texture can soften further. For a dietary swap, use vegetable broth instead of beef broth while keeping the same onion-and-wine method for a vegetarian-friendly version.