Preheat oven to 180 degrees. Butter a 20 cm springform pan.
Whisk the butter, eggs, vanilla, sugar and milk till combined.
Add in the dry ingredients and whisk till smooth. Fold in the chopped apples. The batter will be thick.
Pour into batter into the pan. Bake the cake for ten minutes.
Meanwhile, whisk all the ingredients for topping till smooth. Take out the cake and pour this mixture over it. Return back to the oven and bake for 30 minutes or till done.
Serve warm dusted with icing sugar or with a pouring of custard sauce!