Place the pastry dough with the paper in the spring form tin, press the edge down firmly, firmly prick the base with a fork, chill.
Combine the quark with the cream cheese in a bowl, mix well. Stir in the eggs, sugar, flour and salt. Halve the mixture.
place the chocolate in a thin-sided bowl and suspend over the gently simmering bain-marie, ensuring that the bowl does not touch the water. Melt the chocolate, stir until smooth and stir into half the quark mixture. Pour the white quark mixture over the pastry base, level off and, using a teaspoon, spoon blobs of the dark quark mixture on top.
Bake for approx. 55 mins. in the lower half of an oven preheated to 180°C. Then switch the oven off and leave to rest in the oven for approx. 15 mins., using the handle of a wooden spoon to prop the oven open slightly. Remove, leave to cool and remove from the tin.