01 - Arrange the thinly sliced onion and minced garlic evenly across the bottom of a 6 to 8 quart slow cooker.
02 - Season the beef chuck roast generously with black pepper, then 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 evenly over the beef.
04 - Cover the slow cooker and cook on the low setting for 8 hours, or until the beef is fork-tender and pulls apart effortlessly.
05 - Carefully remove the beef from the slow cooker and shred it using two forks, discarding any excess fat or gristle. Remove and discard the bay leaf from the cooking liquid.
06 - Set the oven to broil and allow it to preheat.
07 - Place the French rolls on a baking sheet. Divide the shredded beef evenly among the rolls and top each with a slice of provolone or Swiss cheese.
08 - Broil the open-faced sandwiches for 1 to 2 minutes, until the cheese is fully melted and the rolls are lightly toasted.
09 - Pour the cooking liquid through a strainer into small individual serving bowls to create the au jus for dipping.
10 - Serve the hot sandwiches immediately alongside the strained au jus for dipping.