For the apple poppy seed tart, first prepare the apple filling. To do this, peel, quarter and core the apples, cut them into small pieces and simmer them with the sugar and vanilla sugar (and a little cinnamon if you like) in a saucepan over low heat.
For the dough, cream the butter until smooth and add the sugar and vanilla sugar, then stir in the egg yolk. Mix the flour with the baking powder, sift and then stir in 2/3 of the flour. Mix in the rest of the flour with your hands to make a crumbly mixture.
For the poppy seed filling, mix the poppy seeds with the hot milk, honey and egg whites. Crumble 2/3 of the dough into a greased springform pan and press it into a flat bottom. Smooth the poppy seed mixture on the dough, spread the apples on top and sprinkle with the remaining dough crumbs. Bake the apple poppy seed cake in the preheated oven at 175 °C for approx. 50 minutes.