Wash, peel and slice the potatoes thinly. In lightly salted, rolling boiling water, cook for 5 minutes. Drain the potatoes thoroughly in a sieve. Take the marjoram from the stalks, and chop finely. Mix salt, pepper and marjoram with the egg yolks and cream. Grease a casserole dish, and place half the potatoes in the form. Chop the ham finely, and spread half over the potatoes. Sprinkle salt and pepper over the layers. Place the rest of the potatoes in the dish, and then pour the egg mix over the top. Sprinkle with ham, and dot the top with the remainder of the butter used for greasing the dish. Cook on 250 degrees Celcius (375F) for 30-40 minutes, or until golden on top. Serve with a green salad. Note: For a main meal, use minced meat and prepare it the same way as for lasagna. Then just alternate the layers of meat mix and the potato recipe.