Separate the eggs for the sponge cake. Beat the egg white and 1 pinch of salt until stiff. Add sugar and vanilla sugar. Stir in the egg yolks one by one. Mix flour, baking powder and almonds and fold in carefully. Spread the mixture on a baking tray (approx. 35 x 40 cm) lined with baking paper.
Bake the sponge cake in a preheated oven (electric cooker: 180 °C/circulating air: 160 °C/gas: see manufacturer) for approx. 10 minutes. Let them cool down.
For the vanilla cream, halve the vanilla pod lengthwise and scrape out the pulp. Whip the cream in 2 portions until stiff, while pouring in 1 sachet of cream stiffener each time. Whip the sour cream, jam sugar and vanilla pulp with the whisk of the mixer for approx. 2 minutes. Fold in the cream in portions.
Turn out the sponge cake onto a plate, remove the baking paper. To make the sponge cake fit better in the refrigerator, cut it into 2 pieces if necessary. Spread the cream on the sponge cake and refrigerate for about 1 hour. Spread red fruit jelly on top.
For the red fruit jelly (makes 2 glasses of approx. 500 ml each): 2 kg of mixed berries (e.g. raspberries, earth berries, blueberries and red currants) sorted or washed. Clean and quarter the strawberries. Strip currants from the stalks. Cut 1 vanilla pod in half lengthwise and scrape out the pulp. Mix 250 ml cherry nectar with 500 g jam sugar (3 : 1), 1 cinnamon stick, vanilla pod and pulp in a pot. Bring to the boil while stirring and boil fizzy for about 3 minutes. Add fruit and continue cooking for about 3 minutes. Immediately fill into prepared glasses with twist-off lids and close them. Let cool off. Store in a cool and dark place. Shelf life: approx. 2 months