Season the chuck roast with salt and pepper. Heat the oil in a skillet and sear the beef until deeply browned on all sides, about 3-4 minutes per side.

Place the onion and garlic in a 6-quart slow cooker. Add the broth, soy sauce, Worcestershire, thyme, and bay leaf. Nestle the roast in the liquid. Cover and cook on LOW for 8-10 hours or HIGH for 5-6 hours.

Transfer the roast to a bowl and shred with two forks. Skim fat from the cooking liquid, then return the meat to the juices and toss to coat.

Broil the split rolls buttered cut side up for 1-2 minutes until golden. Add provolone to the bottoms and broil 30-60 seconds more until melted.

Pile the warm shredded beef onto the cheese-topped rolls, close with the toasted tops, and serve with bowls of the warm au jus for dipping.