Begin by seasoning the beef short ribs generously with salt and pepper. Heat a large Dutch oven over medium-high heat and add a splash of olive oil. Sear the short ribs for 2–3 minutes on each side until they develop a deep, golden-brown crust. Once browned, remove them from the pot and set aside on a plate.

In the same Dutch oven, add 2 tablespoons of butter and 1 tablespoon of olive oil over medium-low heat. Toss in thinly sliced onions with a pinch of salt, stirring occasionally. Allow them to cook for about 45–60 minutes, until they turn deep golden brown and caramelized.

Once the onions are beautifully caramelized, stir in 2 minced garlic cloves and a teaspoon of fresh thyme. Sauté for an additional minute until fragrant, then sprinkle 2 tablespoons of all-purpose flour over the onion mixture. Stir continuously for 2 minutes.

Carefully pour in a cup of red wine while scraping up any browned bits stuck to the bottom of the pot. Let the wine simmer for 3–4 minutes, allowing it to reduce by half.

Return the seared short ribs to the Dutch oven, adding 4 cups of beef broth, a tablespoon of Worcestershire sauce, and 1 bay leaf. Bring the mixture to a gentle boil, then reduce the heat to low and cover partially. Allow it to simmer for 2 to 2.5 hours until the beef is fork-tender.

Once the soup is cooked, carefully remove the short ribs from the pot. Shred the beef from the bones and return the tender meat to the broth, discarding the bones and bay leaf.

While the soup simmers, preheat your broiler. Slice the baguette into thick pieces and toast them under the broiler until golden.

Ladle the soup into bowls, float the toasted baguette on top, and sprinkle generously with freshly grated Gruyère cheese.

Place the bowls under the broiler for 2–3 minutes, or until the cheese is bubbly and lightly browned.