Cut leek and potatoes into slices, sauté both in oil. Add the diced ham and season generously with salt, pepper and marjoram.
For the sauce: mix whipped cream, egg and wine and fold in three quarters of the cheese. Pour the mixture into a greased baking dish and pour the sauce over it.
Bake in the heated oven at medium heat for 30 minutes. Then sprinkle the remaining cheese on top of the casserole and bake repeatedly until the cheese is melted and nice and golden brown.
Tip: Always use an aromatic ham, it will give your dish a wonderful touch!