Season the beef chuck roast evenly with salt and black pepper on all sides.
Heat olive oil in a large skillet over medium-high heat. Sear the beef roast on all sides until browned, about 3-4 minutes per side.
Place the sliced onion and minced garlic in the bottom of the slow cooker.
Transfer the seared beef roast on top of the onions and garlic in the slow cooker.
In a bowl, whisk together beef broth, soy sauce, Worcestershire sauce, dried thyme, and dried rosemary.
Pour the broth mixture over the beef in the slow cooker.
Cover and cook on low for 8 hours, or until the beef is very tender and easily shredded with a fork.
Remove the beef from the slow cooker and shred it using two forks.
Strain the cooking liquid into a saucepan and bring to a simmer over medium heat. Let it reduce slightly for about 10 minutes to concentrate the flavors.
To assemble sandwiches, slice the sandwich rolls in half and layer shredded beef on the bottom half.
Place a slice of provolone cheese on top of the beef.
Top with the other half of the roll.
Serve each sandwich with a small bowl of the warm au jus for dipping.