Creating Rich & Flavorful French Onion Soup is straightforward if you follow these steps:

1. Melt Butter and Oil: In a large pot, heat the butter and olive oil over medium heat until melted.
2. Add Onions: Stir in the sliced onions and sprinkle with salt. Cook, stirring occasionally, for about 30-40 minutes until the onions are caramelized and golden brown.
3. Add Sugar: Stir in the sugar and continue cooking for another 10-15 minutes to enhance the sweetness of the onions.
4. Add Garlic: Add the minced garlic and cook for an additional minute, stirring continuously to prevent burning.
5. Sprinkle Flour: Sprinkle the flour over the onions, mixing well to combine. Cook for about 2 minutes.
6. Add Broth and Wine: Pour in the beef broth and white wine. Stir well to fully combine.
7. Add Thyme and Season: Add fresh thyme, freshly ground black pepper, and any additional seasonings to taste.
8. Simmer: Bring the soup to a boil, then reduce the heat and let it simmer for about 30 minutes.
9. Prepare Bread: While the soup simmers, preheat your oven to 350°F (175°C). Place the sliced baguette on a baking sheet, and toast until crispy. This should take about 10-15 minutes.
10. Serve Soup: Ladle the hot soup into oven-safe bowls. Place a slice or two of the toasted bread on top.
11. Add Cheese: Generously sprinkle the shredded Gruyère cheese over the bread.
12. Broil: Transfer the bowls to the oven and broil for about 5 minutes or until the cheese is bubbly and golden brown.
13. Garnish and Enjoy: Carefully remove from the oven. Garnish with fresh parsley, if desired, and serve hot.

These steps will guide you to create a remarkably rich and flavorful experience in every bowl.