Extract all the meat from the crabs. Wash and reserve the shells.
Finely chop the garlic and anchovies, then fry them gently in a little of the butter for about 3 minutes. Add the vermouth, lemon juice and remainder of the butter, and season with the nutmeg and a good dash of hot pepper sauce to taste. Stir in half of the bread crumbs and the crabmeat. Season with salt and pepper to taste. Stir to blend and cook for about 5 minutes. Add most of the chopped parsley.
Transfer the buttered crab mixture to the crab shells, and sprinkle with the remaining bread crumbs and parsley. Cook under a preheated hot grill until bubbling and brown.