In a large skillet over medium-high heat, add the olive oil and sear the beef chuck roast on all sides until browned (about 3-4 minutes per side). This will enhance the flavor of the beef.
Transfer the seared beef to a crockpot. Add the sliced onion and minced garlic on top of the roast.
In a measuring cup, mix the beef broth, Worcestershire sauce, thyme, and black pepper. Pour this mixture over the beef and onions in the crockpot.
Cover the crockpot and cook on low heat for 8-10 hours, or on high for 4-6 hours, until the beef is fork-tender.
Once cooked, remove the beef from the crockpot and place it on a cutting board. Shred the beef using two forks.
Toast the hoagie rolls if desired. Fill each roll with the shredded beef, and top with some sautéed onions and a slice of provolone cheese, if using.
Ladle some of the beef broth from the crockpot into small bowls for dipping. Serve the sandwiches hot alongside the broth.
Notes
Optional toppings include provolone cheese and fresh parsley.