Boil the potatoes in their skins in salted water, until easily pierced with a fork, about 25-30 minutes.
Peel, then press through a sieve or ricer while still warm.
Let cool, shape into a mound, make a well in the centre, break in the egg, add a pinch of salt, and work in enough flour to form a dough that isn't too firm.
Knead well, then on a floured board, roll into short, finger-thick noodle shapes.
Cook in plenty of boiling salted water for 3-4 minutes, until they rise to the surface, then drain.
Meanwhile heat the lard or butter, add the breadcrumbs, and toast until golden brown.
Toss the cooked noodles with the toasted breadcrumbs, and serve hot.
Based on: Malatinszky Fanny szakácskönyve (a classic Hungarian cookbook), modernised. Calories and protein are estimated.