For the apple pie, cream butter, sugar, vanilla sugar and eggs, add flour, baking powder and rum (or liqueur). Pour the dough into a greased pan, cover with apple slices, press them lightly into the dough.
Place in the preheated oven and bake at 170 °C for about 60 minutes. Warm the apricot jam a little and brush it over the cake, let it cool down and enjoy.