For the shortcrust dough (kruche ciasto)
400 g plain flour
85 g powdered (icing) sugar
250 g cold unsalted butter - cubed
4 large egg yolks
1 tsp baking powder
1 tbsp vanilla sugar - or 2 tsp vanilla extract
3 tbsp sour cream - 45 g, optional, for tenderness
1/4 tsp salt
For the apple filling
1.5 kg tart apples - about 1.2 kg once peeled and cored
60 g granulated sugar - to taste; tart apples need more
1 1/2 tsp ground cinnamon
2 tbsp lemon juice
3 tbsp breadcrumbs or semolina - 30 g, to line the base
For the topping
1-2 tbsp powdered (icing) sugar - for dusting