Combine 300g flour, 60g butter, 60g quark, 3 tablespoons sugar, 1 egg, 3 tablespoons milk, 1 pinch salt, ½ tablespoon vinegar, and ½ bag baking powder. Knead by hand for 5-7 minutes until smooth. Roll out thinly (about 3-4 mm thick) with a rolling pin.
In a bowl, mix the 3 grated apples with cinnamon to taste. Add optional sugar and raisins if desired.
Spread the apple filling down the middle of the rolled dough. Fold the long sides of the dough over the filling.
Place the pastry seam-side down on a baking sheet lined with parchment paper.
Pierce the pastry 3-4 times with a fork. Bake in a preheated oven at 175°C (350°F) using convection heat for 25 minutes until golden brown.