Clean, wash and cut the rhubarb into pieces. Mix starch and 4 tablespoons of cherry nectar. Boil up the rest of the nectar, 1 packet of vanilla sugar and 1 tablespoon of sugar. Weigh 300 g rhubarb, add and simmer covered for about 5 minutes.
Stir in the starch and simmer for about 2 minutes while stirring. Let it cool down.
Line a baking tray (approx. 35 x 40 cm) with baking paper. Separate the eggs. Beat the egg whites and 1 pinch of salt until stiff, adding 100 g sugar and 1 packet of vanilla sugar. Beat the egg yolks separately.
Sift flour and baking powder on top and fold in. Spread on the baking tray. Bake in the preheated oven (electric cooker: 200 °C/circulating air: 175 °C/gas: level 3) for approx. 10 minutes. Turn out immediately onto a tea towel sprinkled with 2-3 tbsp. sugar.
Carefully remove the baking paper. Roll up the sponge cake plate together with the cloth from the long side, let it cool down.
Soak gelatine in cold water. Whip 250 g cream until stiff, adding 2 tablespoons of sugar and 1 sachet of vanilla sugar. Squeeze the gelatine, dissolve over low heat and stir in 2-3 tbsp. stiff cream.
Then fold into the remaining cream. Unroll the sponge cake plate again. Spread with cream, leaving about 2 cm free around the edges. Spread the compote in blobs on top. Roll up the sponge cake and chill for about 4 hours.
Whip 250 g cream until stiff. Either fill into a piping bag with punched spout (size 8) and decorate the sponge roll lengthwise with cream strips. Or coat the roll with the cream. Crumble the meringue, sprinkle over it, press down lightly.