Heat olive oil in a skillet over medium high heat. Brown the chuck roast on both sides for a few minutes to develop flavor.
Place the seared roast into the slow cooker and scrape any browned bits from the skillet into the pot.
Sprinkle the ranch dressing mix and au jus gravy mix over the roast. Pour the beef broth and pepperoncini juice around the meat.
Arrange the carrots, potatoes, and whole pepperoncini peppers around the roast inside the slow cooker.
Lay the butter slices over the top of the roast. Cover and cook on low for about 8 hours, until the beef becomes fork tender.
Pull the roast apart with two forks and mix it with some of the cooking juices before serving.