Soak beef round in cold water 1 hour; drain and rinse well. Wrap beef securely in cheesecloth; place on a rack in a large stock pot, and cover with water. Add molasses; bring to a boil. Reduce heat; cover and simmer 3 hours or until beef is tender. (Allow 15 minutes of cooking time per pound of meat. )
Remove stock pot from heat; set aside. Allow beef to cool completely in cooking liquid in stock pot. Remove from cooking liquid; discard cooking liquid. Chill beef round overnight. Remove cheesecloth. Trim darkened outside areas.
Transfer beef round to a serving platter. Cover top with parsley, and garnish with olives and crab apples, if desired. Cut diagonally across the grain into thin slices; serve with Horseradish- Mustard Sauce.