Whip the soft butter with sugar, adding one egg each during whipping, add vanilla sugar, salt, baking powder and flour. Beat until smooth.
Put the dough in a parchment-covered form, flatten and lay the apricot halves on top. If the apricot is not very sweet, sprinkle a little sugar.
Bake apricot sponge cake at 180 degrees for about 40 minutes, check readiness with a toothpick. Sprinkle with powdered sugar.
The apricot sponge cake is ready, cut into slices and serve.