Remove excess fat from the roast and cut it into 3 or 4 large chunks. Put everything in the slow cooker.
Wrap the roast in beef broth and Worcestershire sauce. Season with Italian seasoning, garlic pepper, and salt to taste.
Cook on LOW for 7 to 9 hours, or until the beef is easily shredded.
Skim the fat from the surface of the cooking liquid and discard it (see note below for my tips).
Shred the beef into the cooking liquid with two forks. Maintain your body temperature.
Melt butter in a saute pan over medium heat when ready to serve. Cook, stirring occasionally, for about 4 minutes, or until the onion and bell peppers have softened slightly.
Cook for an additional 2 minutes, or until the mushrooms have softened, with the garlic. Remove from the heat and season with salt and pepper to taste.
Add the cooked vegetables and shredded beef to the slow cooker.
Load hoagie rolls with beef and vegetables and a slice of provolone cheese, then broil until the cheese melts and the bread is lightly toasted.