The plums are washed, dried, the seeds are removed and cut in half.
The sugar, 120g, is mixed with cinnamon.
In a tray (35x25) greased with butter, sprinkle the sugar mixed with cinnamon on its entire bottom.
Place the plums with the skin facing up, side by side with spaces as small as possible between them.
Sprinkle with hazelnuts and chopped walnuts to enter the spaces between the plums.
Sprinkle with vanilla sugar and a little cinnamon.
In a bowl, beat the egg whites with a pinch of salt.
Add the sugar, 160g, and mix until it hardens.
Add the yolks mixed with the baking powder and mix.
Add the milk and oil and continue mixing.
At the end, add the flour and mix well with a spatula so as not to leave it.
The composition is poured over the plum plums.
Place in the preheated oven at 180 degrees C for 30-35 minutes.
Check with a toothpick if it is done.
Turn over on a plate as soon as it is removed from the oven and left to cool.
After cooling, portion and serve.