Growing up, most visits to my grandparents’ place involved tea time (which really just meant snacks for us kids). I have fond memories of this cake, as it made regular appearances at tea time every summer. I suppose it may not really be an upside down cake in the usual sense…Oma always kept the cake in the tray it was baked in, and simply sliced and served each piece upside down. I’m not entirely sure whether it’s possible to invert the whole cake onto a plate, but I wouldn’t want to mess with tradition, anyway (Royce confirms – yes, it is possible). As it turns out, this recipe comes together quite easily and is a fantastic way to use up plums when in season (Italian prune plums, to be specific – I used another variety of plums once and was promptly notified of my blunder). As fate would have it the Katsumi farm has both (Italian prune) plum and hazelnut trees, and both are starting to produce quite generously.