Wash and peel the potatoes. Place in a saucepan with oneinch of boiling water containing one teaspoon of the salt. Cover and cook until the potatoes are tender but not mushy.
Drain the potatoes if necessary and mash until fluffy with the butter, nutmeg, remaining salt, the pepper and egg yolk. Beat the egg white until it stands in soft peaks and fold it into the potato mixture.
Put enough fat in a heavy skillet to make a layer one-halfinch deep; heat. Drop the potato mixture, a heaping teaspoon at a time, into the hot fat. Fry until brown. Drain on paper towels. Garnish with fresh parsley.