Pat chuck roast dry with paper towels.
Season both sides with salt and pepper.
Place roast in slow cooker.
Sprinkle ranch seasoning evenly over top.
Sprinkle au jus mix evenly over top.
Place butter on top of roast.
Arrange pepperoncini peppers around roast.
Pour pepperoncini juice over everything.
Cover with lid.
Cook on low 8 hours or high 4 to 5 hours. Low is better.
Check if meat is fall-apart tender. Cook 30 more minutes if needed.
Remove roast to serving platter.
Shred with two forks.
Pour gravy from slow cooker over meat. Stir to coat.
Serve hot over mashed potatoes, rice, noodles, or with bread.