Put the flour in a bowl, make a depression in the middle and crumble the yeast. Sprinkle sugar over it and mix the yeast with the water and some flour. Cover the pre-dough and let it rise in a warm place for about 20 minutes.
Add salt and fat and knead the dough well. Put the yeast dough into a bowl and let it rise covered in a warm place for 20-30 minutes until the dough has visibly increased in size. In the meantime peel and halve apples and cut out the core.
Cut apples into thin slices. Mix sour cream with egg yolk, sugar and ground hazelnuts. Grease the tart mould (24 cm Ø). Roll out yeast dough thinly on a lightly floured work surface the size of the tart mould, place in the mould and press down lightly.
Cut off any excess dough. Prick the base of the dough several times with a fork and pour the sand casting on top. Spread the apple slices fan-shaped on the base. Bake in the preheated oven (electric cooker: 225 ° C/ convection oven: 200 °C/ gas: level 4) for approx. 25 minutes.
Cover in between if necessary. Roast the hazelnut leaves in a frying pan until golden brown and remove them immediately. Warm up the apple jelly in a pot. Remove the apple tart from the oven and spread the apple slices thinly with the jelly.
Sprinkle with the roasted hazelnut leaves. Place the cranberries as small heaps in the middle and around the edge. The apple tart tastes very good warm as a sweet main meal with a cinnamon cream.
But it can also be served cold as a small cake with your afternoon coffee.