Fruit Cake Crumble / Streusel für Obstkuchen

A very easy, simple and reliable recipe for Streuselteig (crumble), nearly identical to the one in my mother's cookbook. I tested both this recipe and the one I received from my godmother, and while both of them tasted nice and crisp, I prefered my godmother's one, which contained more butter and sugar in proportion to flour than this one.

Pictured: One base recipe, layered with (clockwise from top left) canned mandarines, fresh rhubarb, canned apricots and cherries from a glas. We used one crumble recipe on the apricots and and part of the cherries, and another one on the rest of the cherries - but I forgot which one went where! Aside from testing different flavours, we also wanted to know how much the different types of fruit would sink into the batter. Apricots were heaviest, rhubarb and cherries were lightest, which means you will have to use more cherries and rhubarb that you would use apricots to actually cover the batter (if you don't, you'll find yourself with a cake that contains fruit within instead of on top).