Peel and dice the apples and drizzle with a little lemon juice.
Mix the butter, sugar, vanilla sugar and salt together well. Add the eggs one by one and stir in well, then the egg liqueur, as well as flour and baking powder. Mix the dough well. Finally, dab the apples lightly and fold into the batter.
Pour the dough into the mold and bake at 175 ° C (fan oven 150 °) for 60 minutes.