Cut the apples into thin slices, crumble the macaroons, chop the walnuts and mix everything together with cinnamon and a little sugar. On the side, mix the remaining sugar with butter, grappa, lemon peel and 1 egg yolk. Once they are well mixed together, add flour, semolina, baking powder and salt; make a dough but remember that the pastry will be quite lumpy. Lay half of the pastry into a pyrex dish, buttered and dusted with flour. Put on top the apples prepared previously and cover with the remaining pastry, pressing it down slightly at the borders. Whip up the egg whites, fold them into the egg yolks, the icing sugar and the cream. Spread the mixture on the cake and cook for an hour in the oven (not pre-heated) at 180ºC.