Spray the insert of a 7-quart slow cooker with cooking spray.
Rub all surfaces of the chuck roast with 1 tablespoon of the olive oil, the salt, and the pepper.
In a large nonstick skillet, heat the remaining 1 tablespoon olive oil over medium-high heat. Add the roast and sear all sides until browned.
While the meat is browning, place the sliced onion in the slow cooker in one layer.
Transfer the roast to the slow cooker and pour the broth and Worcestershire sauce over. Add the bay leaf, cover, and cook on Low for 6 to 8 hours.
Transfer the meat to a cutting board to cool for 10 minutes. Skim any excess fat from the juices in the slow cooker. Slice the meat into very thin slices and return it to the juices in the slow cooker on the Warm setting until serving time.
Preheat the broiler. Open hoagie rolls and toast on a baking sheet under the broiler, just until golden brown. Place slices of the roast on the bottom halves of the rolls and use a slotted spoon to add some onion slices.
Serve with the sauce on the side for dipping.