Russian "plucked cake" with quark filling

Method
Prep:45min  ›  Cook:1hr  ›  Ready in:1hr45min 

For the cake:

1. In a large bowl, combine the flour, cocoa and baking powder and mix well.
2. Beat the butter with sugar until light and fluffy.
3. Add butter-sugar mixture to flour mixture; the mixture will look crumbly.
4. Add eggs, one at a time. You will end up with a soft mixture. Put in the fridge while preparing the filling.

For the filling:

5. Beat eggs with sugar until mixture increases in volume and looks lighter in colour.
6. Continue beating and gradually add quark, butter, cream, vanilla sugar, salt and lemon zest (if using).
7. Preheat oven to 180 C / 160 C fan / Gas 4. Grease a 24 to 28cm cake tin and dust lightly with flour.
8. Take the cake mixture out of the fridge, divide into two. Roll out one of the pieces to line the base of the prepared cake tin, allow the base to come a little way up the sides before trimming away any excess. Pour the quark filling into the base.
9. Pinch or "pluck" little pieces from the second piece of cake dough, placing evenly over the top of the filling.
10. Bake in the preheated oven for 45 to 60 minutes, depending on the size of your tin. Remove from the oven and allow to cool before slicing and serving.