Boil potatoes until soft, peel and press through potato ricer while still hot. Mix with butter, flour, yolks, semolina and salt to a dough. Depending on the moisture of the potatoes, you may need a little more flour.
Let dough rest for 10 minutes.
Form dough into a roll on a floured surface and cut into 20 slices. Flatten dough slices, place an apricot on each and cover with dough. (If you don’t want apricot seeds in the finished dumplings, you can press them out of the apricots with a wooden spoon handle and fill the apricots with sugar cubes instead).
Steep dumplings in lightly salted water for 10 to 12 minutes (do not boil!).
Meanwhile, for butter crumbs, heat butter, add crumbs, cinnamon and granulated sugar and toast until golden, stirring constantly.
Lift the dumplings out of the water with a sieve ladle, drain well and roll in the butter crumbs. Serve the apricot dumplings sprinkled with powdered sugar.