Peel and chop the onion. Heat the oil in a saucepan and fry the onion until translucent. Add the spinach and 3 tablespoons of water and cook until the spinach is thawed, stirring occasionally and seasoning with salt, pepper, paprika and nutmeg.
Finely mash the potatoes and mix with the cream cheese, egg yolk, half of the cheese and the herbs and stir to a pulp. Divide the mass into 6 parts and shape so that one slice of ham can be wrapped around each part of the mass.
Put the spinach in a greased baking dish. Place the filled ham rolls on top. Scatter the rest of the cheese over the ham rolls. Bake at 225 degrees (fan oven 190 degrees) for about 15 minutes.