1. Preheat the oven to 190°C (375°F). Line two baking sheets with baking parchment and set aside. 

2. For the streusel add the flour, sugar, butter, and vanilla extract to a bowl and rub between your fingers to get different sized streusel. Place in the fridge until needed.

3. Wash and dry the cherries, then pit them. Set aside.

4. Add the curd (Quark), oil, egg, and sugar for the dough to a large bowl and mix to combine. Mix the flour with baking powder, and salt and add to the bowl – knead until you get a nice and smooth dough. Divide into 8 pieces, form each piece into a ball, pull apart to create oval rounds with a length of about 5.9 inches (15cm). The edges should be slightly thicker than the centers of the dough pieces. Place them on the baking sheets with some space in between. Add the pitted cherries on top, sprinkle with the raw cane sugar and the streusel. Brush the edges with some milk and bake for 16-20 minutes until the streusel are golden brown. Take the pastries out of the oven and place them on a wire rack. Brush the edges of the still warm plum pastries with some apricot jam (optional) and let cool down. Decorate with sugar glaze (optional) and serve.