For the basic dough melt the butter and let it cool down a little. Mix flour, sugar, vanilla sugar and 1 pinch of salt in a large bowl or pot. Add the liquid butter and knead everything into crumbles using the dough hooks of the mixer.
Divide the crumble into 4 portions. Knead other ingredients under the individual portions according to taste. For the rhubarb crumble, grate marzipan and knead into a crumble portion. Cover and chill for approx. 20 minutes.
Preheat oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer). Clean, wash and cut the rhubarb into pieces. Pour the frozen raspberries into a greased ovenproof dish.
Sprinkle with 3-4 tablespoons of sugar and spread the marzipan crumble on top.
Bake Crumble in a hot oven for 35-40 minutes. Dust with some icing sugar and serve warm.