Coat a 6-quart slow cooker with nonstick spray.

Warm the oil in a cast iron skillet over medium-high heat. Season the roast all over with salt and pepper, then sear on both sides until golden. Add to the slow cooker and top with the beef broth, water, Worcestershire sauce, beefy onion soup mix, and all seasonings.

Cook on LOW for 4 hours. Remove roast and transfer to a cutting board. Thinly slice the roast across the grain. Place sliced meat back in the slow cooker and continue to cook on LOW for another 1-2 hours.

Remove the roast from the slow cooker and strain fat from the broth to have a clean au jus.

Split the rolls open and fill them with the beef and some shredded cheese. Place the sandwiches onto a baking sheet under the broiler until the cheese is melted and golden or alternatively, place them in a 350?F preheated oven.

Garnish sandwiches with minced parsley and serve with a bowl of the au jus for dipping.