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Julia Child’s French Onion Soup (Soupe à l’Oignon Gratinée)

Course Main Dish
Cuisine French
Keyword chicken Noodle Soup
Prep Time 20 minutes
Cook Time 2 hours
Servings 6 servings

Equipment

Ingredients

For the soup

  • 5 Cups yellow onions thinly sliced
  • 3 Tbsp unsalted butter
  • 1 Tbsp neutral oil, vegetable or canola
  • 1 tsp salt
  • ¼ tsp sugar
  • 3 Tbsp flour
  • 8 Cups beef stock or brown stock boiling
  • ½ cup dry white wine or dry white vermouth
  • Freshly ground black pepper to taste
  • 3 tbsp cognac optional

For the croutons and gratin top

  • 1 large baguette or crusty French bread sliced into ¾–1 inch rounds
  • 1 clove garlic cut in half
  • 2 cups grated Swiss or Gruyère cheese or a mix with Parmesan
  • 1 Tbsp. olive oil or melted butter

Instructions

Soften the Onions

  • Melt the butter with the oil in a heavy pot over medium heat.
  • Add the sliced onions, toss to coat, cover the pot, and cook over low heat for about 15 minutes until soft and translucent.

Brown the Onions Deeply

  • Remove the lid, raise the heat slightly to medium‑low, and add the salt and sugar.
  • Cook, stirring frequently for 30 minutes up to an hour, or until the onions are a deep golden brown and have liquified; lower the heat or add a spoonful of water if they threaten to burn.

Add Flour

  • Sprinkle the flour over the onions and stir until all the slices are lightly coated.
  • Cook for 2–3 minutes, stirring, so the flour loses its raw taste and forms a light roux with the onion juices.

Build and Simmer the Soup

  • Bring the beef stock to a boil in another pot.
  • Off the heat, stir a ladle of the hot stock into the onions to loosen the browned bits, then add the rest of the stock and the wine or vermouth.
  • Season with pepper (and additional salt if needed), return to a gentle simmer, and cook uncovered for about 30 minutes.
  • If using cognac, stir it in at the end of the simmer.

Make the Croutons

  • Heat the oven to 325–350°F (160–175°C).
  • Arrange the bread slices on a baking sheet and bake until dry and crisp all the way through.
  • Rub each hot slice lightly with the cut side of the garlic clove.

Assemble and Gratinée

  • Taste the soup and adjust seasoning; it should be robust and well‑salted.
  • Ladle hot soup into oven‑safe bowls set on a baking sheet.
  • Float 1–2 slices of toasted bread on each portion, then cover generously with grated cheese.
  • Float 1–2 slices of toasted bread on each portion, then cover generously with grated cheese.
    Drizzle the oil or butter on top which will help the cheese melt
  • Bake at 325°F for about 20 minutes, until the soup is bubbling and the cheese is fully melted.
  • Finish under the broiler for a few minutes to brown and lightly crust the top
  • Let the bowls rest briefly before serving; they will be very hot.