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french onion soup recipe with caramelized onions, toasted baguette, and melted gruyere cheese

French Onion Soup Recipe

This french onion soup recipe is built on two pounds of slowly caramelized onions, finished with a splash of dry sherry and ladled under a thick lid of melted Gruyère. It looks like you spent all day — and you kind of did, but mostly just waiting on the onions.
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Prep Time 15 minutes
Cook Time 1 hour 15 minutes
Total Time 1 hour 30 minutes
Servings: 6 servings
Calories: 420
Ingredients Method Nutrition Notes

Ingredients
  

  • 3 lbs yellow onions about 5–6 medium onions; they shrink dramatically so don't go light
  • 4 tablespoons unsalted butter do not substitute olive oil here
  • 1 tablespoon olive oil combined with butter to raise the smoke point
  • 1 teaspoon sugar to nudge the caramelization along
  • 1 teaspoon salt added early to draw moisture out of the onions
  • 3 cloves garlic cloves minced
  • 1/2 cup dry sherry Cognac works too; avoid cooking wine
  • 4 cups good-quality beef broth use the best quality you can find for maximum flavor
  • 2 cups chicken broth mixing with beef broth gives depth without heaviness
  • 2 fresh thyme sprigs
  • 1 bay leaf
  • black pepper to taste
  • 1 baguette sliced into 3/4-inch rounds; day-old works great
  • 2 cups Gruyère cheese freshly shredded; pre-shredded has a coating that prevents proper melting

Method
 

  1. Peel and thinly slice the yellow onions into half-moon shapes, about 1/4-inch thick. Try to keep them uniform so they cook evenly.
  2. In a large heavy-bottomed pot or Dutch oven, melt the butter with the olive oil over medium heat. Once the butter is foamy, add all the sliced onions and stir to coat.
  3. Add the salt and sugar to the onions and stir to combine. Cook over medium to medium-low heat, stirring every 5–10 minutes, for 45–60 minutes. The onions need to reduce significantly and turn a deep amber-brown color. Do not rush this step — low and slow is the key to true caramelization.
  4. Once the onions are deeply caramelized, add the minced garlic and cook for 1–2 minutes, stirring constantly, until fragrant.
  5. Pour in the dry sherry and scrape up any browned bits from the bottom of the pot. Let it cook for 2–3 minutes until the sherry is mostly absorbed and the sharp alcohol smell has mellowed.
  6. Add the beef broth, chicken broth, fresh thyme sprigs, and bay leaf. Stir to combine. Bring the soup to a boil, then reduce the heat and let it simmer uncovered for 20–25 minutes to allow the flavors to meld.
  7. While the soup simmers, preheat your oven broiler to high. Arrange the baguette slices on a baking sheet and broil for 1–2 minutes per side until lightly toasted and golden. Watch them closely — they go from golden to burnt quickly.
  8. Remove the thyme sprigs and bay leaf from the finished soup. Taste and adjust seasoning with black pepper and additional salt if needed.
  9. Set oven-safe broiler-proof bowls on a rimmed baking sheet. Ladle the hot soup into each bowl, filling about 3/4 full. Place one or two toasted baguette slices on top of the soup in each bowl.
  10. Generously pile freshly shredded Gruyère over the baguette slices in each bowl, covering the bread completely and slightly overlapping the edges of the bowl.
  11. Slide the baking sheet under the broiler and broil for 3–5 minutes, watching carefully, until the cheese is fully melted, bubbling, and spotted with brown in places. Serve immediately while the cheese is still molten.

Nutrition

Calories: 420kcalCarbohydrates: 38gProtein: 18gFat: 22gSaturated Fat: 12gSodium: 980mgFiber: 4gSugar: 12g

Notes

The soup itself tastes even better the next day as the broth deepens overnight. Build the crouton and cheese topping fresh each time, even when reheating. Use freshly shredded Gruyère — pre-shredded has a coating that prevents proper melting. Do not substitute cooking wine for the sherry; use a dry sherry you would actually drink. Yellow onions are the classic choice and caramelize better than red onions without turning bitter.

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