Peel and dice the potatoes, cook in salted water until soft. Pour off the water, let the potatoes steam out. Bring the milk, cream and marzipan to the boil, season with nutmeg, salt and pepper. Use the press to add the potatoes to the liquid, add the butter and whip with a wooden trowel until airy. (not with the hand blender, otherwise Puree will be tough!)