Separate 4 eggs. Beat the egg whites and 2 tablespoons of water until stiff. Finally, pour in 125 g sugar. Stir in egg yolk. Mix flour, cornstarch and baking powder, sieve onto the egg foam and fold in loosely. Smooth the dough on a baking tray (38 x 32 cm) lined with baking paper. Bake in a preheated oven (electric cooker: 200 °C / fan-assisted oven: not suitable/ gas: level 3) for approx. 12 minutes. Take out, place on a cake rack and let cool off.
In the meantime soak the gelatine in cold water. Wash the grapes, dab dry and, except for a few berries for decoration, pluck them from the stalks. Separate 4 eggs. Mix the egg yolks and 75 g sugar until creamy. Add white wine and lemon zest. Warm up the lemon juice to 2 tablespoons and remove from the heat. Squeeze out the gelatine well and dissolve it in it. Mix gelatine with 3 tablespoons of the cream. Stir into the remaining cream and refrigerate for about 10 minutes. In the meantime, whip the cream until stiff and allow the vanillin sugar to trickle in. Beat the egg whites and 1 pinch of salt until stiff. When the cream starts to gel, fold in 300 g cream and beaten egg white one after the other. Turn out the sponge cake onto a work surface and carefully remove the baking paper. Halve the sponge cake crosswise. Place one half of the sponge cake on a board and spread with about half of the cream.
Stir into the remaining cream and refrigerate for about 10 minutes. In the meantime, whip the cream until stiff and allow the vanillin sugar to trickle in. Beat the egg whites and 1 pinch of salt until stiff. When the cream starts to gel, fold in 300 g cream and beaten egg white one after the other. Turn out the sponge cake onto a work surface and carefully remove the baking paper. Halve the sponge cake crosswise. Place one half of the sponge cake on a board and spread with about half of the cream. Spread grapes on top. Spread the rest of the cream on top and cover with the second base. Press lightly and smooth the edges. Then spread with the remaining cream (200 g). Put in a cool place for about 2 hours. Dip the remaining grapes in lemon juice, roll in sugar and let dry. Cut the cake into 10 approx. 6 x 9 cm slices. Arrange the slices on a plate and serve decorated with the sugared grapes
Spread grapes on top. Spread the rest of the cream on top and cover with the second base. Press lightly and smooth the edges. Then spread with the remaining cream (200 g). Put in a cool place for about 2 hours. Dip the remaining grapes in lemon juice, roll in sugar and let dry. Cut the cake into 10 approx. 6 x 9 cm slices. Arrange the slices on a plate and serve decorated with the sugared grapes
waiting time approx. 2 hours