Coat a 6-quart slow cooker with nonstick spray.

Warm the oil in a cast iron skillet over medium-high heat. Season the roast with salt and pepper, then sear on both sides until golden.

Add the roast to the slow cooker and top with the beef broth, water, Worcestershire sauce, beefy onion soup mix, and all the seasonings.

Cook on LOW for 4 hours. Remove the roast and transfer to a cutting board. Thinly slice the roast across the grain.

Place the 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 obtain au jus.

Split the rolls open and fill them with the beef and some shredded cheese. Place the sandwiches on a baking sheet under the broiler until the cheese is melted and golden (watch carefully to avoid burning). Alternatively, place them in a 350°F preheated oven.

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