You can scold me for coming up with this recipe now, add the end of plum season. But the cake is too good to vanish for another year in the draft folder and I had to wait to try this idea for to long time. Problem was the freeze during spring that left us nearly no good plums. And so I had to wait for the late plums until baking this cake.
The special twist I longed to try was baking the streusel separately. This helps do avoid soaked streusel and adds a nice crunch to the cake. The cake itself and the streusel recipe as well are old friends you know already. But combined they make a great team. Save the recipe for next year in case you get no plums any more!