Steps
1. Slice the onions thinly.
2. In a large pot, melt the butter over medium heat. Add the onions and garlic, and sauté until caramelized and golden brown.
3. Pour in the beef broth, red wine, Worcestershire sauce, sugar, salt, and pepper. Bring to a simmer and let cook for 20 minutes.
4. Meanwhile, preheat the broiler. Place the slices of French bread on a baking sheet and toast until golden brown.
5. Ladle the soup into oven-safe bowls. Top each bowl with a slice of toasted French bread and sprinkle with grated Gruyere cheese.
6. Place the bowls under the broiler until the cheese is melted and bubbly.
7. Serve hot and enjoy!