In your slow cooker add the chuck roast.

To a mixing bowl or cup add the brown gravy mix, au jus mix, onion powder, celery seed, black pepper and beef broth.

Stir to combine.

Pour this mixture over the beef roast.

Top with the butter.

Cook on low for 6-8 hours or high for 4-6 hours until the beef falls apart.

Remove the beef from the slow cooker and shred.

Remove all the liquid from the slow cooker except for about 1 cup.

You can reserve the rest of the liquid for dipping if you like.

Toss the shredded beef with the 1 cup liquid in the slow cooker.

Pile onto soft buns with mayo, lettuce and tomato.