Begin by placing the sliced onion at the bottom of your slow cooker.

Carefully position the seasoned beef roast on top of the onions.

Pour the beef broth, Worcestershire sauce, and soy sauce into the cooker.

Sprinkle the garlic powder, onion powder, thyme, black pepper, and salt over the beef roast.

Cover the slow cooker with its lid and set it to LOW for 8 hours or HIGH for 4-5 hours.

Once the cooking time is complete, carefully remove the beef from the slow cooker and allow it to rest for a few minutes.

Remove the onion pieces from the cooked broth, leaving only the liquid in the slow cooker.

Mix the cornstarch with cold water in a small bowl until smooth, then stir this into the broth in the slow cooker.

Plate your Beef Manhattan by layering the shredded beef over generous servings of creamy mashed potatoes and slice of toasted bread.