Knead a crumble dough from flour, baking powder, butter, sugar and cinnamon, pour half the amount into a greased, square springform pan and press and bake for approx. 12 minutes, then remove and allow to cool for approx. 5 minutes.
In the meantime, whip in the whipped cream, stir in the starch and sugar and add the currants.
Spread this topping on the pre-baked cake base and cover with the remaining crumble dough, then bake for about 30-35 minutes.