Place the beef chuck roast in the slow cooker. Sprinkle the italian dressing mix, garlic powder, dried oregano, and black pepper evenly over the top and sides of the roast.
Pour the entire jar of pepperoncini peppers with their juice over the meat. Add the beef broth to the pot.
Cover and cook on low for 8 to 10 hours or on high for 5 to 6 hours. The beef should be extremely tender and falling apart easily.
Remove the roast from the slow cooker and shred the meat using two forks, discarding any large pieces of fat. Return the shredded beef to the pot and stir it into the juices.
Let the shredded beef sit in the juices for about 10 minutes to soak up all the flavor.
Pile the Italian beef onto hoagie rolls and top each sandwich with a slice of provolone cheese. If desired, broil the open sandwiches in the oven for 1 to 2 minutes until the cheese is melted and bubbly.
Serve with a small bowl of the cooking juices on the side for dipping. The juices make these sandwiches absolutely irresistible.