Place the chuck roast in the bottom of the slow cooker and sprinkle the top with the ranch seasoning mix and the au jus gravy mix. Top with the butter (no need to slice it). Add the peppers on top of the roast.
Cook on LOW heat for 8 hours. When ready, carefully shred the beef with two forks. Discard any fatty pieces. Serve over warm mashed potatoes. Enjoy!
Notes
Do not add any extra water, broth or pepperoncini juice to the slow cooker. The beef and butter will create their own gravy as it cooks.