Zwetschkenfleck mit Haselnussstreusel (Plum cake with hazelnut crumble)

The literal meaning of Zwetschkenfleck is "plum patch". In Vienna it means plum cake, a traditional dessert from the Viennese cuisine.

Ingredients:

300 g (2 ½ cups) flour (fine)
25 g (¼ cup) moist yeast
salt
3 egg yolks
1 cooking spoon vanilla sugar
30 g (1/8 cup) sugar
100 ml milk
rind from 1/2 lemon (grated)
40 g (1/8 cup) melted butter
20-25 small plums, quartered and pitted
150 g (2/3 cup) plum or apricot jam
4 cl rum (0,64 pt) (or plum brandy)
icing sugar (for dusting)
flour (for the work surface)

For the crumble:

120 g (1 1/8 cup) flour
100 g (1 cup) sugar
100 g (½ cup) butter
60 g (¼ cup) raw marzipan
60 g (0,13 lb) hazelnuts (roasted and ground)
salt
1 cooking spoon vanilla sugar
1 pinch of cinnamon

Preparation:

Heat the milk to 30 °C. Crumble in the yeast and stir well. Add the egg yolk, vanilla sugar and sugar, flour, a pinch of salt and the lemon rind. Stir in the melted butter and, using a blender or mixer, mix until it becomes a smooth dough. Cover and leave to rise for 40 minutes. On a floured surface, knead thoroughly. Cover and leave to rise again for about 30 minutes. For the crumble, knead all the ingredients together well, shape into a roll, wrap in foil and leave to sit for 1 hour in a cool place. Line a baking tray with baking paper. Roll out the dough about 8 mm thick to about 30 x 50 cm. Place on the baking tray, spread with warmed jam and, pressing them slightly into the dough, lay the plums with cut side facing up. Dribble over some rum or plum brandy. With a vegetable grater, coarsely grate over the crumble mixture and let sit for 20 minutes. Bake golden brown in a preheated, fan-forced oven at 190 °C for 30-40 minutes. Dust with icing sugar when still warm.