To prepare the cake layer, mix together the flour, sugar, cocoa and baking powder in a bowl to a homogeneous, dry mixture. Melt the butter, add it to the dry mixture. Start kneading with your hands until you obtain sticky crumbs.
Put baking paper at the bottom of a cake form with removable walls (after removing the walls and leaving only the base). Now, place the cake ring on top, to pinch the baking paper between it and the base.
Pour 1/2 the mixture for the cake layer in it, press with a spoon to shape the cheesecake base.
To make the cream mixture you have to use a hand blender, not a mixer, to obtain a fine texture. Pour the cottage cheese and sugar into a bowl and blend for 2-3 min.
Then add the eggs, vanilla sugar and sour cream and blend another 2-3 min. to obtain a smooth cream. Pour it over the base. Sprinkle the rest of the cake mixture evenly over the cream mixture.
Bake at 302°F (150 °C) about 25 min. but be careful not to over-bake, so the cheesecake doesn't end up dry on the inside.
When you take it out of the oven it may seem underbaked and runny but don't worry - the baking time is plenty.
Once the dessert has cooled, put away in the fridge for at least 4-5 hours to harden well.