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French Onion Soup with Gruyère Cheese

French onion soup is slowly cooked until the onions are deeply golden and caramelized, then topped with crisp baguette slices and shredded Gruyère. Broiling the crocks makes the cheese melted, bubbling, and browned in spots.
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Prep Time 20 minutes
Cook Time 1 hour 35 minutes
Resting 5 minutes
Total Time 2 hours
Servings: 6 servings
Course: Dinner
Cuisine: French
Calories: 570
Ingredients Equipment Method Notes

Ingredients
  

For the soup
  • 4 tbsp unsalted butter
  • 1 tbsp olive oil
  • 3 lb yellow onions halved and thinly sliced
  • 1 tsp kosher salt
  • 4 cloves garlic minced
  • 1 tbsp fresh thyme leaves
  • 1 bay leaf
  • 1 cup dry white wine
  • 6 cups low-sodium beef broth
  • 0.5 tsp black pepper
For the topping
  • 1 baguette 12-ounce, cut into 1/2-inch slices
  • 8 oz Gruyère cheese shredded

Equipment

  • 1 6-quart Dutch oven
  • 1 baking sheet
  • 1 rimmed baking sheet
  • 6 16-ounce ovenproof crocks

Method
 

Make the soup
  1. Melt the butter and olive oil in a 6-quart Dutch oven over medium heat.
  2. Add the onions and salt, reduce the heat to medium-low, and cook uncovered for 45-60 minutes, stirring often, until deeply golden and caramelized.
  3. Stir in the garlic and thyme and cook for 1 minute, until fragrant.
  4. Pour in the wine, scraping up browned bits from the pot, and simmer for 3-5 minutes.
  5. Add the broth, bay leaf, and black pepper, and bring to a boil.
  6. Reduce the heat and simmer uncovered for 25 minutes.
  7. Remove the bay leaf.
Toast the bread
  1. Heat the oven to 400°F.
  2. Arrange the baguette slices in a single layer on a baking sheet and bake for 8-10 minutes, turning once halfway through, until crisp and lightly golden.
Assemble and broil
  1. Set an oven rack about 6 inches below the broiler and heat the broiler to high.
  2. Divide the soup among six 16-ounce ovenproof crocks set on a rimmed baking sheet.
  3. Top each crock with 1-2 toasted baguette slices and an even layer of Gruyère.
  4. Broil for 2-4 minutes, watching closely, until the cheese is melted and bubbling with browned spots.
  5. Let the crocks rest for 5 minutes before serving.

Notes

For the best texture, cook the onions slowly until deeply golden rather than rushing the caramelization. Refrigerate leftovers for 3-4 days; freeze the soup without the bread and cheese. For a gluten-free option, use gluten-free baguette.