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French Onion Soup

This classic French Onion Soup features slow-caramelized onions that develop deep sweetness and rich flavor, forming the foundation of a velvety broth. Topped with toasted baguette slices and melted Gruyère cheese, it offers a comforting combination of tender, caramelized onions and crispy bread in every spoonful. The process emphasizes patience and gentle heat to achieve the perfect balance of sweetness and savory depth.
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Prep Time 15 minutes
Cook Time 1 hour 15 minutes
Total Time 1 hour 30 minutes
Servings: 4
Course: Main Course
Cuisine: French
Calories: 450
Ingredients Equipment Method Notes

Ingredients
  

  • 4-5 large yellow onions thinly sliced
  • 2 tablespoons unsalted butter for caramelizing onions
  • 1 cup dry white wine such as Sauvignon Blanc or Pinot Grigio
  • 4 cups beef broth or vegetable broth for vegetarian version
  • 1 sprig fresh thyme optional, for flavor
  • 1 slice baguette cut into 1-inch slices and toasted
  • 1 1/2 cups Gruyère cheese freshly grated
  • 1 tablespoon olive oil for toasting bread if desired

Equipment

  • Large Heavy-Bottomed Pot
  • Sharp knife
  • Baking sheet
  • Oven-safe bowls
  • Wooden spoon

Method
 

  1. Begin by thinly slicing the yellow onions; aim for about 1/8-inch slices that will caramelize evenly.
  2. Place a large heavy-bottomed pot over medium-low heat and add the butter, allowing it to melt slowly with a gentle sizzle.
  3. Add the sliced onions to the melted butter, spreading them out evenly. Cook gently, stirring every 10 minutes, until they turn a deep amber color and smell sweet, about 45-60 minutes. This slow process develops their natural sugars and creates a rich aroma.
  4. Once the onions are deeply caramelized, pour in the white wine and stir, scraping up any browned bits from the bottom of the pot. Allow the wine to reduce for 2-3 minutes until mostly evaporated, intensifying the flavor.
  5. Add the beef broth and a sprig of thyme to the pot. Bring the mixture to a gentle simmer, then reduce the heat to low and cook for another 20 minutes, allowing the flavors to meld and the broth to thicken slightly.
  6. While the soup simmers, arrange the baguette slices on a baking sheet, brush lightly with olive oil if desired, and toast in a preheated oven at 200°C (390°F) for about 10 minutes until golden and crispy.
  7. Remove the thyme sprig from the soup and taste for seasoning, adding salt if needed. Ladle the hot soup into oven-safe bowls, placing a toasted baguette slice on top of each.
  8. Sprinkle a generous layer of freshly grated Gruyère cheese over each bread slice, covering the surface evenly.
  9. Place the bowls on a baking sheet and broil in the oven until the cheese bubbles and turns golden brown, about 3-5 minutes. Keep a close eye to prevent burning.
  10. Carefully remove the bowls from the oven and let sit for a minute to settle. Serve hot, garnished with additional herbs if desired, and enjoy the rich, velvety broth with crispy bread and melted cheese.

Notes

Patience is key in caramelizing the onions; take your time for the best flavor. Feel free to customize with different cheeses or bread types for variety.