Begin by heating a skillet over medium-high heat and adding a drizzle of oil. Sear the beef chuck roast for about 3-4 minutes on each side, until it's beautifully browned.

Transfer the seared beef into the Crockpot, and add in beef broth, Worcestershire sauce, minced garlic, and sliced onion. Stir gently to combine.

Cover the Crockpot with its lid and set it to cook on low for 8 hours, or high for 4-5 hours.

Once cooked, carefully remove the beef from the Crockpot and shred it with two forks. Return the shredded beef back into the Crockpot.

Preheat your oven to 375°F (190°C). Halve the French rolls and toast them cut-side up on a baking sheet for about 5-7 minutes.

Assemble your sandwiches by piling shredded beef onto each roll and adding slices of cheese on top.

Serve your sandwiches warm with a small bowl of the au jus for dipping.