Sear the Beef: Heat a large skillet over medium-high heat. Pat the beef dry and season all sides evenly with salt. Add the vegetable oil to the hot skillet and sear the roast for about 1 to 2 minutes per side until beautifully browned. Transfer it to a large slow cooker and sprinkle with the black pepper.

Make the Broth: Use the same skillet over medium heat. Pour in the water, beef broth, and beef bouillon, stirring to capture all those tasty browned bits from the pan. Once it’s well combined, pour this mixture over the beef in the slow cooker.

Add Flavor: Nestle the bay leaf, minced garlic, and sliced mushrooms around the roast. Sprinkle the onion soup mix generously on top, letting some naturally fall into the liquid. Finally, finish with the thyme and rosemary.

Slow Cook: Cover and cook on LOW for 8 to 10 hours until the beef is incredibly tender and shreds easily. If you need a quicker option, cook on HIGH for 1 hour before reducing to LOW for the remainder.

Slice and Prepare Rolls: Once your meat is perfectly cooked, transfer the roast to a cutting board and let it rest. Slice it thinly against the grain, ensuring every bite is melt-in-your-mouth heaven.

Broil the Rolls: Preheat the broiler. Place the rolls cut-side up on a baking sheet. If you want to get fancy, mix the softened butter with garlic powder and spread it on the rolls. Broil until lightly golden, then flip briefly to crisp the outer crust. Return the rolls to cut-side up, layer on the cheese, and broil again just until it melts.

Assemble: Spread horseradish sauce over the cheesy rolls, then pile on the sliced beef and mushrooms. Close your sandwiches and serve them hot with bowls of the rich cooking jus for dipping.