French Onion Soup

Instructions

1. Caramelize the onions
   In a large, heavy-bottomed pot, melt the butter with olive oil over medium-low heat. Add the sliced onions and toss to coat with the butter mixture. Cover and cook for about 15 minutes until the onions are soft and translucent.
2. Develop deep flavor
   Increase heat to medium and add the sugar to help with caramelization. Cook uncovered, stirring frequently, for 30-40 minutes until the onions turn a deep golden brown. Be patient - proper caramelization takes time but creates the essential flavor foundation.
3. Create the soup base
   Sprinkle the flour over the caramelized onions and stir for 2-3 minutes. Gradually add the beef stock, white wine, bay leaf, and thyme. Season with salt and pepper. Bring to a simmer, then reduce heat to low and cook uncovered for 30 minutes, allowing the flavors to meld together.
4. Prepare the bread
   While the soup simmers, preheat the oven to 350°F (175°C). Place the baguette slices on a baking sheet and toast in the oven until lightly browned, about 5-7 minutes per side. Remove and set aside.
5. Assemble and broil
   Preheat the broiler. Ladle the hot soup into oven-safe bowls placed on a baking sheet. Float 1-2 toasted baguette slices on top of each bowl of soup, then sprinkle generously with grated Gruyère cheese. Broil until the cheese is melted, bubbly, and golden brown, about 2-3 minutes.
6. Serve
   Carefully remove the hot bowls from the oven and let them rest for a minute before serving. The soup should be steaming hot with a golden cheese crust on top.