For the dough, knead the flour, butter, sugar, vanilla sugar and egg well and then chill the dough for about 30 minutes.
Peel the apples for the filling and cut into cubes. Caramelize together with the sugar in a saucepan and then add both lemon juice and cinnamon. Let the apple pieces simmer until they soften and then mash them, preferably with a potato masher, although a few pieces can still be left.
While the apple mixture is cooling, take the dough out of the refrigerator and roll it out to about 3 - 4 mm thick. Cut out squares with sides or circles of equal length from the dough and place some of the (cold) apple mixture in the middle of these shapes. Fold the dough pieces into triangular / semicircular pockets and press the edge into place.
Finally, brush the top of the bags with a little egg yolk and then bake for 20 minutes at 180 ° C in the preheated oven (top / bottom heat).
The quantities given are sufficient for about 10 - 12 apple turnovers.