Rinse the apricots, then cut them in half, remove pits and place a sugar cube in the centers of 12 pieces. Cut the remaining apricots in half, remove pits and set aside. Peel the potatoes and press through a ricer. Combine the potoato with the flour, semolina flour, salt, nutmeg and egg. Knead into a smooth dough. With floured hands, form the dough into a roll and cut it into 12 thin slices. Press an apricot (with sugar cubes) into each slice, and wrap firmly, pressing edges together. Place the dumplings in a pot of lightly salted, boiling water and let cook for 20 minutes.
Melt the butter in a frying pan, add the breadcrumbs and stir until golden brown. Remove from heat, and drain excess butter. Coat the cooked dumplings in the breadcrumbs on a warmed plate, then dust with cinnamon and sugar and serve.