Place the beef chuck roast in a 6-quart slow cooker.
Sprinkle the ranch seasoning and au jus seasoning over the roast. Add the butter, pepperoncini, pepperoncini juice, and beef broth around the meat.
Cover and cook on low for 8 to 10 hours, or until the beef is tender and shreds easily with a fork.
Transfer the roast to a plate and shred it with two forks. Remove large pieces of fat, then return the shredded beef to the slow cooker.
Add the frozen egg noodles and gently press them into the cooking liquid.
Cover and cook on high for 30 to 60 minutes, stirring once or twice, until the noodles are tender.
Rest for 5 minutes, garnish with fresh parsley, and serve warm.