Peel potatoes, cut into fourths, and boil until done. Drain and dry off over low heat. Turn into mashed potatoes. Make them very rich with butter and cream and then thin with a bit of milk. Do not whip in a mixer, but mash with a potato masher. Season with salt, pepper, and nutmeg.
Coat a bread pan with butter. Pack the potatoes into it, keeping them to one end of the pan and to the depth of the pan. Use foil to hold them to one end. Cover and refrigerate until cold and molded into a loaf. Turn the potato cake out onto a floured board and cut into six slices. Flour the slices well and fry on both sides in bacon fat or lard. Have the fat hot before adding the potato slices. (Leftover potatoes may be given the same treatment.)