- 3 lbs onions, peeled and thinly sliced
- 1 tablespoon butter
- 1 tablespoon olive oil
- Salt and freshly ground black pepper
- Pinch of sugar
- 6 cups beef broth
- 1 clove of garlic, smashed
- 1 teaspoon peppercorns
- 1 bay leaf
- 1 sprig fresh thyme
- 1 baguette, cut into 1/2-inch thick slices
- 8 ounces Gruyère cheese, grated
- Heat the butter and olive oil in a large pan over medium heat. Add half the onions and sauté until softened, 3 to 4 minutes. Add the remaining onions and continue cooking, stirring occasionally, until they begin to turn golden brown, 7 to 8 minutes. Season with salt and pepper and add a pinch of sugar. Continue cooking until the onions are nicely caramelized, about 30 minutes longer.
- While the onions are cooking, place the beef broth in a large saucepan and bring to a simmer over medium heat. Add the garlic, peppercorns, bay leaf and thyme. Simmer gently for about 20 minutes, then remove the flavorings with a slotted spoon.
- Once the onions are caramelized, add them to the broth and continue cooking for 20 minutes, stirring occasionally.
- Preheat the broiler. Ladle the soup into 6 small oven-proof crocks and float several slices of baguette on each. Top with the shredded Gruyere and place under the broiler until the cheese is lightly browned and bubbly, 2 to 3 minutes. Serve immediately.