Line a baking tray (approx. 35 x 40 cm) with baking paper. Separate the eggs. Beat the egg whites, 3 tbsp. cold water and 1 pinch of salt until stiff, while pouring in 125 g sugar. Fold in the egg yolks one by one. Sift flour, starch and baking powder on top and fold in
Spread the sponge cake on the tin. Bake in the preheated oven (electric cooker: 200 °C/circulating air: 175 °C/gas: level 3) for approx. 10 minutes. Sprinkle the tea towel with 3 tbsp. sugar. Turn out the sponge cake and remove the baking paper immediately. Cool down
Cut the sponge in half crosswise. Place a sponge cake plate on a board. Wrap a baking frame or a rim of multiple folded aluminium foil (approx. 5 cm high) around it. Sort the raspberries, wash if necessary. Mix quark, 100 g sugar, lemon peel and lemon juice
Whip the cream briefly. Add instant gelatine while stirring constantly with the hand mixer and whip the cream until stiff. Immediately add 2/3 berries to the quark. Spread on the 1st sponge cake plate. Place the 2nd plate on top, chill for about 1 hour
Dust with icing sugar and cut into pieces. Decorate with rest of berries and lemon balm