Creating the Best French Onion Soup Recipe can be straightforward if you follow these simple steps:

1. Cook the Onions: In a large pot, melt the butter and olive oil over medium heat. Add the thinly sliced onions along with salt and sugar. Stir frequently and cook for about 30-40 minutes until the onions are deeply caramelized and golden brown.

2. Sprinkle Flour: Once the onions are caramelized, sprinkle the flour over them and stir well. Continue to cook for an additional 2-3 minutes to get rid of the raw flour taste.

3. Add Broth and Wine: Pour in the beef broth (and wine if using). Stir well and increase the heat to bring the mixture to a simmer.

4. Seasoning: Add the thyme leaves. Allow the soup to simmer gently for about 30 minutes. Taste and adjust seasoning if needed.

5. Prepare the Bread: While the soup is simmering, preheat the oven to 400°F (200°C). Place the baguette slices on a baking sheet and toast them in the oven for about 5-7 minutes until they are lightly browned and crispy.

6. Serve the Soup: Ladle the hot soup into oven-safe bowls. Place a slice or two of toasted baguette on top of each bowl.

7. Add Cheese: Generously sprinkle grated Gruyère cheese on top of the toasted bread.

8. Broil: Place the bowls on another baking sheet and set them under the broiler for about 5 minutes, until the cheese is bubbly and golden brown.

9. Garnish: Carefully remove the soup from the oven. Garnish with freshly chopped parsley if desired.

10. Enjoy: Serve the soup hot, and enjoy the delightful flavor of your Best French Onion Soup Recipe!