1 To make the dough mix together the flour, sugar, vanilla sugar and a pinch of salt. Add the butter and the cream and knead quickly into a shortcrust dough. Wrap in clingfilm and chill for approx. 30 minutes.
2 Heat the oven to 200°C (180°C in a fan oven), 400°F, gas 7 and grease a tart dish.
3 Roll out the dough on a floured work surface to fit the tart dish. Place the dough in the tart dish and create an edge.
4 To make the topping mix the butter and sugar until creamy. Add the eggs one at a time until the mixture is frothy. Mix together the flour and the baking powder and sieve into the mixture. Add the ground almonds and stir in the almond liqueur and the milk. Add the apples and spread the topping evenly on the dough. Sprinkle with the slivered almonds and bake for approx. 45 minutes (test with a wooden stick!). If the tart gets too brown, cover with tin foil.
5 Remove from the oven, leave to cool and sprinkle with icing sugar. Serve with whipped cream.