Preheat the oven to 160°C (circulating air). Whisk the eggs, sugar and vanilla sugar with a stirrer. Add butter or magarine and whisk again until creamy.
Then add the flour, almond flour and the packet of baking powder and mix well.
Line a baking sheet with baking paper and pour the dough on it.
Wash, drain, halve and stone. Place on the cake dough.
Mix together the flour, sugar, vanilla sugar and cinnamon. Add the soft butter. Knead briefly with your hands to a crumbly dough.
First, place the cake with the plums in the oven for 10 minutes. After 10 minutes, spread the crumble over the plums and bake for another 40 minutes.