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. Transfer the roast to the slow cooker.
Add the sliced onion and minced garlic to the skillet and sauté for 2-3 minutes until softened. Transfer onions and garlic to the slow cooker, placing them on top of the roast.
Pour beef broth and Worcestershire sauce over the roast in the slow cooker. Sprinkle dried thyme and rosemary evenly over the top.
Cover and cook on low for 8 hours, or until the beef is very tender and easily shredded with a fork.
Once cooked, remove the roast from the slow cooker and place on a cutting board. Shred the beef using two forks.
Strain the cooking liquid from the slow cooker into a saucepan and bring to a simmer over medium heat to reduce slightly for the au jus, about 5-7 minutes.
Preheat the oven broiler. Place the sandwich rolls cut side up on a baking sheet. Layer shredded beef evenly on the bottom halves of the rolls, then top each with a slice of provolone cheese.
Broil the sandwiches for 2-3 minutes or until the cheese is melted and bubbly. Remove from the oven and top with the roll tops.
Serve each sandwich hot with a small bowl of the warm au jus for dipping.