Roast the garlic bulbs in the oven at 400°F until deeply golden and fragrant, about 40 minutes, then let them cool slightly.
Heat olive oil in a large Dutch oven over medium-high heat, then sear the beef roast until browned on all sides, about 4-5 minutes per side. Tongs help turn the meat for an even crust.
Add diced onion to the pot and cook until translucent, about 3 minutes, stirring occasionally. This releases a savory aroma and softens the onion.
Squeeze the softened roasted garlic cloves out of their skins and mash them lightly with a fork to release their rich aroma. Add the mashed garlic to the pot along with chopped herbs, stirring to coat the beef and onions.
Pour in the beef broth, scraping the bottom of the pot to loosen any browned bits, which add depth of flavor. Season with salt and pepper.
Cover the Dutch oven with a lid, then transfer it to the preheated oven at 325°F. Let it cook slowly for about 2.5 to 3 hours, until the beef is incredibly tender and easily shredded.
Once cooked, remove the pot from the oven and carefully transfer the beef to a cutting board or serving platter. Let it rest for a few minutes to allow the juices to redistribute.
Meanwhile, skim off any excess fat from the cooking liquid if desired, then simmer for a few minutes to concentrate the flavors and thicken slightly.
Shred the beef with two forks and spoon some of the flavorful sauce and herbs over the top. Serve hot, garnished with additional fresh herbs if you like.
Enjoy the tender, herb-infused beef with its fragrant crust and rich, savory juices, perfect for a cozy family dinner.