For the semi-silk, boil the potatoes, peel them and press them through the potato ricer while still hot.
Bring the milk to the boil in a saucepan and add to the potatoes with the cornflour and salt and knead well. Then let stand for 15 minutes.
Cut the rolls into small cubes and fry in butter.
Form dumplings from the potato dough and fill them with the bread cubes. Steep in plenty of salted water for about 20 minutes.
Serve the finished semis hot.