For the crumble, put the butter in a bowl. Add the flour and sugar and mix everything together, then set aside for the time being.
Then mix all the ingredients for the dough together and stir well, so that a nice, smooth batter is created. Then drain the plums and mix them with a little cinnamon in an extra bowl.
Put the dough in a greased baking tin, add the drained plums and distribute evenly, pressing in a little if necessary. Finally, sprinkle the sprinkles on top.
Then bake the cake at 180 ° C for about 30 minutes, until the crumble on top turns a very light brownish color.