Peel and slice the potatoes, place them in a greased oven dish and stir gently with the pre-chopped ham. Season with salt, black pepper and white pepper, a pinch of oregano and sprinkle on the chopped leeks.
Pour in a little oil on top and a little warm water. Beat the cream in advance and pour it over the dish. Put to bake for 30 minutes on moderate heat in the oven under foil. Remove the foil and then bake finished to a nice tan.