– 4 large onions, thinly sliced

– 2 tablespoons butter

– 1 tablespoon olive oil

– 2 cloves garlic, minced

– 1 teaspoon fresh thyme (or 1/2 teaspoon dried thyme)

– 1 bay leaf

– 4 cups beef broth

– 1 cup chicken broth

– 1/2 cup dry white wine (optional)

– Salt and pepper to taste

– 8 slices of baguette or French bread, toasted

– 1 1/2 cups shredded Gruyere cheese

1. Melt butter with olive oil in a large pot over medium heat. Add the sliced onions and cook, stirring occasionally, until they are caramelized and golden brown, about 30-40 minutes.

2. Add the minced garlic, thyme, and bay leaf. Cook for another minute.

3. Pour in the beef broth, chicken broth, and white wine (if using). Bring the soup to a boil, then reduce the heat and let it simmer for 15-20 minutes. Season with salt and pepper to taste.

4. Preheat the broiler. Ladle the soup into oven-safe bowls. Place a toasted slice of bread on top of each bowl of soup and sprinkle with shredded Gruyere cheese.

5. Place the bowls under the broiler until the cheese is melted and bubbly, about 2-3 minutes.

6. Carefully remove the bowls from the oven and let them cool slightly before serving.