Trim the fat from the roast. Coat the roast with garlic powder and pepper. In a Dutch oven, brown the roast on all sides in hot oil. Place the browned roast in the crockpot insert.
In a medium bowl, whisk together the beef broth, dressing mix, onion salt, oregano, basil and parsley. Pour the mixture over the roast in the crockpot. Top with pepperoncini peppers and pour ½ cup of the pepperoncini juice on top too.
Cover and cook on low-heat setting about 10 hours. Transfer the cooked meat to a cutting board. Using two forks, pull the meat apart into shreds. Using a slotted spoon, remove the peppers from the cooking liquid and transfer them to a serving bowl. Skim the fat from the cooking liquid; and then transfer the skimmed liquid to a bowl.
Preheat your oven's broiler. To serve, spoon some shredded meat onto the bottom half of the buns. Sprinkle with cheese. Place the sandwiches under the broiler to melt the cheese. Then spoon the desired amount of cooking liquid over the meat. Top with peppers and bun tops.