Ingredients:

  • 4 large yellow onions, thinly sliced (about 1.6 kg)
  • 4 cups beef stock (960 ml) or vegetable stock
  • 3 tablespoons unsalted butter (45 g)
  • 1 tablespoon olive oil (15 ml)
  • 1 teaspoon sugar (5 g)
  • 1 tablespoon all-purpose flour (8 g)
  • 2 teaspoons fresh thyme leaves or 1 teaspoon dried thyme
  • 1 bay leaf
  • Salt and black pepper to taste
  • 4 slices of French bread or baguette, toasted
  • 1 ½ cups grated Gruyère cheese (170 g)
  • Optional: Fresh parsley, chopped for garnish

Instructions:

  1. Heat the pot over medium heat, add butter and olive oil. Add sliced onions, cook for 30-40 minutes, stirring occasionally until deeply caramelized and soft.
  2. Sprinkle with sugar halfway through to enhance sweetness.
  3. Stir in the flour, cook for an additional 2 minutes. Add thyme, bay leaf, and season with salt and pepper.
  4. Gradually pour in the beef or vegetable stock, scraping the bottom to release any delicious bits. Simmer uncovered for 20 minutes.
  5. Preheat the broiler. Place toasted bread slices on a baking tray, top with grated cheese.
  6. Remove bay leaf, ladle the soup into oven-safe bowls, and float the cheesy bread on top.
  7. Broil until the cheese is bubbly and golden (3-5 minutes).
  8. Garnish with parsley and serve hot.