Making Slow Cooker Beef Manhattan is easy if you follow these simple steps:

1. Prepare the Beef: Trim excess fat from the beef chuck roast and cut it into large chunks. This helps it to cook evenly.
2. Mix the Sauce: In a large bowl, combine the onion soup mix, beef broth, water, Worcestershire sauce, minced garlic, black pepper, and salt.
3. Layer in the Slow Cooker: Place the beef chunks in the slow cooker and pour the sauce mixture over the top. Ensure all beef is covered.
4. Cook: Set the slow cooker to low for 8 hours or high for 4 hours. Cover and let it cook undisturbed.
5. Check for Tenderness: Once the cooking time is up, check the beef. It should be fork-tender and easily shreddable.
6. Thicken the Gravy (optional): If a thicker sauce is desired, mix cornstarch with a little cold water in a small bowl. Stir this mixture into the slow cooker and let it cook for an additional 30 minutes on high.
7. Prepare the Rolls: While the beef is finishing, lightly toast the hoagie rolls in the oven until golden brown.
8. Assemble the Dish: Shred the beef with forks directly in the slow cooker or transfer to a serving dish. Serve generous portions of the beef and gravy on toasted rolls.
9. Garnish: Sprinkle fresh parsley over the top for a fragrant finish.

Now you’re ready to enjoy a hearty meal packed with flavors and satisfying goodness.