01 - Arrange the sliced onion and minced garlic evenly across the bottom of the slow cooker insert.
02 - Rub the chuck roast thoroughly with salt, black pepper, dried thyme, and dried rosemary. Place the seasoned roast directly on top of the onion layer.
03 - Pour the beef broth, soy sauce, and Worcestershire sauce over the roast and vegetables.
04 - Cover the slow cooker and cook on low heat for 8 hours until the beef pulls apart easily with a fork.
05 - Transfer the cooked beef to a cutting board. Using two forks, shred the meat into bite-sized pieces. Return the shredded beef to the slow cooker and stir well to absorb the au jus.
06 - Set the oven to broil. Split the hoagie rolls open and pile them with the shredded beef. Top each sandwich with a slice of provolone or Swiss cheese.
07 - Arrange the assembled sandwiches on a baking sheet. Broil for 2 to 3 minutes, watching closely, until the cheese is melted and bubbly.
08 - Ladle the remaining au jus from the slow cooker into small dipping bowls. Serve the hot sandwiches immediately alongside the au jus.