Heat a large skillet over high heat. Sear the beef chuck roast on all sides until browned, about 2-3 minutes per side.

In a small bowl, mix together the ranch dressing mix and au jus gravy mix.

Place the seared beef chuck roast in a slow cooker. Sprinkle the seasoning mix over the roast.

Add the butter and pepperoncini peppers to the slow cooker.

Cover the slow cooker and cook on low for 8 hours or on high for 4-5 hours, until the meat is tender and falls apart easily.

Once cooked, remove the beef from the slow cooker and shred it using two forks.

Serve the Mississippi Pot Roast hot, with the juices spooned over the top. Enjoy with your favorite side dishes such as mashed potatoes, rice, or roasted vegetables.