Creating this French Onion Beef Short Rib Soup can be straightforward by following these steps:

1. Prepare the Beef: Season beef short ribs with salt and pepper. In a large pot, heat olive oil over medium-high heat. Sear short ribs on all sides until browned (about 3-4 minutes per side). Remove from pot and set aside.

2. Sauté Onions: In the same pot, reduce heat to medium and add butter. Add sliced onions and cook for about 20-30 minutes, stirring often until they become golden brown and caramelized.

3. Add Garlic and Herbs: Stir in minced garlic, thyme, and cook for an additional minute until fragrant.

4. Deglaze Pot: Pour in the white wine (if using) and scrape the bottom of the pot to release any browned bits. Let it simmer until the wine is reduced by half.

5. Combine Ingredients: Return short ribs to the pot and add beef broth. Toss in the bay leaf and bring to a gentle boil.

6. Simmer: Reduce heat to low, cover, and let it simmer for 2 hours, or until beef is tender and falling off the bone.

7. Shred Beef: After cooking, remove short ribs from the pot. Allow them to cool slightly, then shred the meat, discarding the bones and excess fat.

8. Finish Soup: Return the shredded beef to the pot. Taste and adjust seasoning with salt and pepper as needed.

9. Prepare Baguette: While the soup simmers, preheat your oven to 400°F (200°C). Place sliced baguette on a baking sheet and top each slice with a generous amount of grated Gruyere cheese. Toast in the oven until cheese melts and is bubbly (about 5-7 minutes).

10. Serve: Ladle the hot soup into bowls and top with a slice of the cheesy baguette. Garnish with fresh parsley if desired.