Cook the potatoes in
plenty of boiling salted water until tender. Drain
and return to the pan for a few moments to dry out.
Rub through a sieve or potato ricer into a bowl (do
not blend in a processor or the mixture will go
runny).
Season well with salt and pepper, then mix
in the nutmeg and flour. Stir in the egg and beat
thoroughly until smooth.
With floured hands, shape
the mixture into 24 small balls. Drop into a large
pan of boiling water, a few at a time, and cook for
about 5 minutes or until they rise to the surface.
Transfer with a draining spoon to a warm serving
dish and keep warm.
When all the gnocchi are cooked,
drizzle with the melted butter and sprinkle with
Parmesan cheese before serving.