Season the chuck roast with salt and pepper.
Sear the roast on all sides in a hot skillet until browned.
Place the seared roast in a slow cooker.
Sprinkle the ranch dressing mix evenly over the roast.
Sprinkle the au jus gravy mix on top.
Add the pepperoncini peppers and their juice around the roast.
Place the butter on top of the roast.
Cover the slow cooker and cook on low for 6-8 hours.
Once done, shred the meat with two forks inside the cooker.
Serve hot, garnished with fresh parsley.