Preheat the oven to 325°F. Remove the leaves from a head of savoy cabbage, halve them, and then cut them into wide strips. Blanch the leaves in salted, boiling water for 4 minutes. Remove the leaves from the water and then drain them.
Wash and peel the potatoes, cut them into slices, and then cook them for about 4 minutes in the same water you used to blanch the savoy cabbage leaves. Remove the potatoes from the pot and drain them.
Remove the apple cores with an apple corer, cut the apples into thin slices, and immediately add the lemon juice to the slices to keep them from browning.
Stack the ham slices on top of one another and cut the entire stack into quarters.
Grease a casserole dish and layer the potato, apple, and ham slices with the cabbage leaves. Then mix the cream, eggs, milk, salt, pepper, and nutmeg and pour the dressing over the casserole.
Mix the bread crumbs, hazelnuts, and melted butter until you have a crumbly topping to spread on top of the casserole. Bake for 35 minutes.