01 -
Add the chicken broth, beer, and Dijon mustard to the slow cooker. Add the corned beef (discard the juices from the package) and sprinkle the seasoning packet on top along with the garlic and bay leaves. Place the sliced onions in the liquid around the meat.
02 -
Slice the potatoes in half (they should be about 2-inches wide). Arrange the carrots and potatoes around the perimeter of the slow cooker, packing them closely so there's room to add cabbage later.
03 -
Cover and cook on low for 8 hours. A 6-quart slow cooker will be full but the meat will render down and make more room for the cabbage later.
04 -
Add the cabbage wedges to the top of the slow cooker, packing them in tightly. Close the lid and cook for 2 more hours.
05 -
Transfer the cabbage, potatoes, and carrots to a serving platter and tent with foil. Carefully move the corned beef to a cutting board, tent with foil, and let rest for 15 minutes. Slice against the grain, sprinkle with parsley, and serve with butter, salt, and pepper.