Mix the blueberries, sugar and lemon zest in a pan. Combine the cornflour with the lemon juice, add to the pan and bring to the boil while stirring, simmer for approx. 1 min. and leave to cool.
Bring the cream to the boil in a small pan. Remove the pan from the heat, stir in the gelatine, pour into a bowl through a sieve. Stir in the quark and icing sugar. Carefully fold in the whipped cream and half of the blueberries using a rubber spatula.
Place the springform pan on a cake plate. Place the sponge fingers in the tin with the sugared side facing down, cut to size if necessary. Arrange half of the remaining blueberries on top of the sponge fingers, spread the quark mixture over the top. Decorate with the remaining berries. Cover the cake and leave to set in the fridge for approx. 4 hrs. Carefully remove the tin frame.