Heat the oil in a frying pan and saute the onion and garlic over a very low heat untilthe onion is soft.
Add the tomatoes, increase the heat and cook until the mixture is thick and well blended. Add the parsley, wine , sugar, salt and pepper plus a dash of cayenne and cook for 3-4 minutes over a moderate heat.
Add the shredded crab meat and cook for 3 minutes more.
Pile the mixture into crab shells or gratin dishes. Sprinkle with the breadcrumbs and dot with butter. Bake in a preheated oven 200 C, 180 Fan, Gas 6 for about 10 minutes until the top is lightly browned.
Serve with a mixed green salad and a crisp dry white wine.