1. Place the brisket in a 6-quart slow cooker and generously salt and pepper on all sides.
2. Pour the beef broth and Worcestershire sauce around the brisket. Scatter the onions, garlic, rosemary and bay leaf around the roast.
3. Place the lid on the slow cooker and cook on low for 8 hours, or on high for 4 to 5 hours, until the roast is tender and can almost be pulled apart with a fork.
4. When the roast is finished cooking, remove from slow cooker and place on a cutting board or other work surface. Cover with foil and allow to rest.
5. Combine the cornstarch and water, whisking thoroughly to fully incorporate. Remove the rosemary and bay leaf from the cooking juices and add the cornstarch mixture. Whisk to thoroughly combine, replace the lid, and cook on high until it’s thickened into a gravy. Adjust seasoning to taste if necessary.
6. Slice the beef brisket (it may also come apart in chunks on its own, and I kind of like that presentation too). Serve with gravy on the side.
Pro tip: The entire roast and gravy can be made a day ahead of time. Cook as above, but do not slice the brisket.
Place the brisket on top of the gravy, and let everything cool completely before removing the slow cooker insert and placing in the refrigerator. The next day, you can simply place the insert back into the slow cooker heating element and bring it back up to temperature.
