Place corned beef in large pot, and cover with water and one can of beer. Add the spice packet. Cover pot, and bring to a boil. Reduce heat. Add brown sugar, onion and bay leaves. Simmer 3-1/2 hours. Skim top if needed. Add potatoes, carrots, garlic and cabbage, and cook until the vegetables are tender. Remove meat, and slice across the grain. Or combine all ingredients in a slow cooker on low for 6 hours.