Mix flour with baking powder in a large bowl. Stir in 100g sugar, vanilla sugar and salt. Add the butter and egg. Work everything into a smooth dough. Wrap and chill for 1 hour or overnight.
Peel apples, quarter, core and then finely chop either in the food processor or by hand. In a cup, mix 2 tablespoons sugar with cinnamon and toss with apples (use more or less of cinnamon-sugar depending on sweetness of apples).
Preheat oven to 190 C / Gas 5. Grease a round springform cake tin with butter.
Line base and sides of tin with 2/3 of the chilled dough. Pour in apple mixture and roll out remaining dough into a circle. Place circle of dough on top of the apples, sealing the pastry together at the sides. If there is any leftover dough, cut out pretty shapes and decorate the pie.
Bake in preheated ovven for 40 minutes. Lower oven temperature to 180 C / Gas 4 and bake for an additional 30-40 minutes.