In a large pot or Dutch oven, heat the olive oil over medium-high heat. Season the beef cubes with salt and pepper, then brown them in batches until golden on all sides. Remove the beef and set aside.

In the same pot, add the sliced onions and cook over medium heat, stirring frequently, until they are caramelized and golden brown, about 15-20 minutes. Add the minced garlic and cook for an additional 1-2 minutes.

Sprinkle the flour over the onions and stir to combine. Cook for 1 minute, then gradually add the red wine, scraping up any browned bits from the bottom of the pot.

Return the beef to the pot and add the beef broth, Worcestershire sauce, thyme, and rosemary. Bring to a simmer, then cover and cook on low heat for about 1.5 to 2 hours, or until the beef is tender.

Preheat your oven to 375°F. Once the stew is ready, ladle it into oven-safe bowls or a baking dish. Top each portion with cubed French bread and a generous amount of grated Gruyère cheese.

Bake in the preheated oven for 15-20 minutes, or until the cheese is bubbly and golden brown.

Remove from the oven and let cool slightly. Garnish with fresh parsley before serving.