For the plum cake, mix flour, powdered sugar, eggs and oil to a smooth dough, mix in the baking powder at the end.
Spread the dough on a baking sheet.
Stone and halve the plums and spread them on the cake. Sprinkle with cinnamon if desired and bake the plum cake in the oven at 180 °C top/bottom heat for about 30-40 minutes.
Preparation Tip:
Make the plum cake with crumble.