Grease a 26 springform pan and sprinkle the bottom with breadcrumbs. Make a stirring part from the ingredients for the base and fill it evenly into the springform pan. Scatter the currants over the base. Cook a vanilla pudding and then stir in the sour cream. The filling can now be spread over the base. Spread the finished crumbles evenly over the cake filling. Bake in the preheated oven at 180 °C top/bottom heat on the lowest shelf for approx. 45 minutes.