Separate eggs. Beat the egg whites and 2 tablespoons of cold water with the whisks of the hand mixer until stiff. Add sugar, 1 packet of vanilla sugar and salt to finish. Beat the egg yolks one after the other. Mix flour, cocoa and baking powder, sieve onto the egg yolks and fold in carefully
Put the sponge mixture on a baking tray (32 x 39 cm) lined with baking paper, smooth it down. Bake in the preheated oven, middle shelf (electric oven: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for approx. 10 minutes. Turn out onto a damp tea towel sprinkled with a little sugar. Carefully remove the baking paper. Wrap the sponge cake plate in a damp cloth and let it cool down for about 30 minutes
Soak gelatine in cold water. Whip 400 g cream and 2 packets of vanilla sugar until stiff. Squeeze the gelatine, dissolve and mix with approx. 1 tbsp. cream. Add the gelatine to the rest of the cream while stirring, spread on the sponge cake, leaving an approx. 1 cm wide rim all around. Roll up the sponge cake from one long side using a tea towel. Chill for about 2 hours.
Whip 100 g cream until stiff, allowing the cream firmer to trickle in. Pour cream into a piping bag with a small perforated spout. Dust the roll with icing sugar and decorate with cream. Chill the roll for about 15 minutes. Arrange the roll on a plate with currants as desired
Waiting time approx. 2 1/2 hours