01 - Arrange the thinly sliced onion and minced garlic in an even layer across the bottom of the slow cooker.
02 - Generously coat the chuck roast on all sides with kosher salt, black pepper, dried Italian seasoning, basil, and oregano, pressing the spices into the meat.
03 - Place the seasoned roast on top of the onion and garlic bed in the slow cooker.
04 - Pour the beef broth and pepperoncini juice over the roast. Sprinkle in the crushed red pepper flakes if using.
05 - Cover and cook on LOW for 8 hours or on HIGH for 5 to 6 hours, until the beef is fork-tender and shreds apart effortlessly.
06 - Transfer the roast to a cutting board. Using two forks, pull the beef apart into shreds, discarding any large pieces of excess fat. Return the shredded meat to the slow cooker and toss to absorb the juices.
07 - Optionally, spread softened butter on the cut sides of each roll and toast them under the broiler until golden and crisp.
08 - Mound the shredded beef generously onto each roll. Layer two slices of provolone cheese on top and scatter with sliced pepperoncini.
09 - For a melty finish, place the open-faced sandwiches under the broiler for 1 to 2 minutes until the cheese is bubbling. Serve immediately while warm.