Quarter cabbage, cutting away and discarding core. Cover with boiling water and let stand for five min. Drain and pat dry and shred. Set aside. In heavy pan over lo heat, melt butter and simmer chopped onion until tender without browning. Add cabbage and potato and stir over low heat. Add mace. Stir in flour to coat all ingreds., but do not brown. Add liquids, bring to boil, and simmer for 20 min. or until vegs. are tender. Dump in blender and blend until almost smooth, but still a little lumpy. Reheat and add salt and pepper to taste. If it seems too thick, add a bit of hot milk. Serve with scoop of whipped cream and a sprinkling of parsley and cheese on top.