Make a shortcrust pastry from 250 g all purpose flour, 80 g granulated sugar, 100 g butter, 1 pinch of salt, 1 teaspoon baking powder and 1 egg. Place all the ingredients in a bowl and knead by hand to form a ball of dough. Then wrap the dough in cling film and leave to rest in the fridge for an hour.
Meantime wash 1 kg plums, remove the stalks, cut in half with a knife and remove the pits.
Streusel
Pour 150 g all purpose flour, 80 g granulated sugar, 100 g butter, 1 pinch of salt, 1/2 teaspoon ground cinnamon and 1 pinch of ground cardamom into a bowl and knead by hand. The dough is moist and not crumbly, reminiscent of shortcrust pastry. Put the bowl with the crumble dough to one side.
Line the base of a springform pan with baking paper. Then grease the inside of the pan and dust with flour.
In the meantime, preheat the oven to 160°C or 320°F.
Topping the cake
Take the shortcrust pastry out of the fridge and shape into a roll. Divide the roll into 1/3 and 2/3. Roll out 1/3 of the dough into a circle (the size of the base of the springform pan). Then place the shortcrust pastry on the base of the springform pan.
Roll out the remaining dough (2/3) to a width of approx. 8 cm and line the inside of the springform tin with it. Then press the pastry down well on the base and inside with your fingers. If the top edge looks a little "frayed", you can smooth it out with your fingers.
Place the halved and pitted plums in the springform pan from the outside in. I place the plum halves upright on the shortcrust pastry so that they don't lie flat in the cake. This way, the cake is baked nice and high.
Spread the crumble over the cake. Pluck small pieces of crumble from the dough and sprinkle them over the plums.
Place the cake in the oven and bake for approx. 50 minutes. After baking, leave the plum cake to cool in the tin.
Notes
To prevent the cake from getting mushy, you can sprinkle some gelling sugar* over the plums before adding the crumble. You can find lots more useful tips in my post.