01 - Arrange the thinly sliced onion and minced garlic evenly across the bottom of the slow cooker.
02 - Season the chuck roast generously with black pepper and place it on top of the onion and garlic bed.
03 - In a mixing bowl, whisk together the beef broth, soy sauce, Worcestershire sauce, dried thyme, dried rosemary, and bay leaf. Pour the mixture over the beef.
04 - Cover the slow cooker and cook on low for 8 hours, or until the beef is fork-tender and pulls apart easily.
05 - Transfer the beef to a cutting board and shred using two forks, discarding any large pieces of fat. Remove and discard the bay leaf from the cooking liquid. Strain the liquid into small serving bowls to use as au jus.
06 - Turn the oven broiler to high. Arrange the rolls on a baking sheet, pile each with shredded beef, and top with a slice of provolone or Swiss cheese. Broil for 1–2 minutes until the cheese melts and the rolls are lightly toasted.
07 - Serve the hot sandwiches immediately with individual bowls of warm au jus on the side for dipping.