Roughly chop all the nuts, halve the grapes, peel and core the apples and cut into thin slices. Immediately drizzle with the lemon juice. Layer with the grapes in a greased baking dish and spread the rum raisins on top.
Mix the yoghurt with the eggs, honey, vanilla sugar and lemon peel well and spread over the apples. Scatter the nuts on top, cover everything with flakes of butter.