Preheat the oven to 60 °C and warm a plate.
Combine the butter, vanilla sugar and salt in a bowl, mix well. Whisk in the egg and quark. Mix the semolina, flour and baking powder, add and mix to form a soft, smooth dough, cover and chill for approx. 2 hrs.
Blitz the bread in a food processor or chop finely. Heat the butter in a frying pan, add the bread and sugar, toast and stir over a medium heat until golden, transfer to a deep dish.
Divide the dough into 12 portions, flatten slightly. Fill two apricot halves with a sugar cube, place on top of each piece of dough. Wrap in the dough and shape into balls with floured hands. Cook the dumplings in batches in simmering water for approx. 15 mins. Remove with a slotted spoon, toss in the breadcrumbs, keep warm.