French Onion Soup with Gratinéed Baguette

In a large, heavy-bottomed pot, melt the butter with the olive oil over medium heat. Add the thinly sliced onions and season with salt. Cook slowly, stirring frequently, for 30-40 minutes until the onions are deeply golden brown and caramelized. Add the minced garlic and cook for another 1-2 minutes.

Pour in the white wine (if using) and scrape up any browned bits from the bottom of the pot. Let the wine evaporate for 2-3 minutes. Sprinkle in the all-purpose flour, stir to combine, and cook for 1 minute. Gradually whisk in the beef broth, then add the bay leaf and thyme. Bring to a boil, then reduce heat and simmer for 20-25 minutes to allow the flavors to meld. Season with salt and freshly ground pepper to taste.

Preheat your oven to broiler setting or 200°C (400°F). Slice the baguette into 1.5-2 cm thick rounds. Arrange them on a baking sheet and toast lightly in the oven for 5-7 minutes until golden.

Ladle the hot soup into oven-safe bowls. Place 2-3 toasted baguette slices on top of each bowl of soup, then generously sprinkle with grated Gruyère cheese. Place the bowls under the broiler for 5-10 minutes, or until the cheese is melted, bubbly, and golden brown. Carefully remove and serve immediately.