Peel, core, and slice the apples and stew to a pulp with 2 oz. (4 Tbs.) sugar but no water.
Heat the margarine in a frying pan.
Add the breadcrumbs and rest of the sugar and cook until crisp, stirring frequently.
Grease the tin and put in a layer of crumbs, then a layer of the apple, and repeat these, finishing with crumbs.
Bake in a moderate oven for 1/2 hour and leave to cool.
Turn out on a large dish and sprinkle the chocolate on top.
Cut in wedges to serve.
Hand the sauce separately.