Firstly, beat the egg whites to stiff peaks with 100 g sugar.
Beat the softened butter vigorously with the remaining 100 g sugar, add the egg yolks gradually and then add the rest of the ingredients in this order: buckwheat flour, grated hazelnuts and baking powder. Add the grated apples and lemon rind, which were previously mixed together. Keep mixing until smooth.
Stir the beaten egg whites gradually into the mixture, stirring delicately with an upward motion.
Bake in pre-heated oven at 180°C for about 40 minutes. When cooled, cut into two layers and fill with redcurrant jam.
For this cake you can prepare homemade redcurrant jam! Just boil 1 kg redcurrants with 300 g sugar and grated rind of one lemon for 30 minutes. Put in jars and let cool.
Recipe from Baita Checco