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 onions and minced garlic in the bottom of the slow cooker.
Transfer the seared beef roast to the slow cooker on top of the onions and garlic.
In a bowl, combine beef broth, soy sauce, Worcestershire sauce, dried thyme, and dried rosemary. Pour the 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. Return the shredded beef to the slow cooker and stir to combine with the cooking juices.
Preheat the oven broiler. Slice the sandwich rolls in half and place the bottom halves on a baking sheet.
Divide the shredded beef evenly among the bottom halves of the rolls. Top each with a slice of provolone cheese.
Place the baking sheet under the broiler for 2-3 minutes, or until the cheese is melted and bubbly.
Serve each sandwich with a small bowl of the warm au jus from the slow cooker for dipping.