Separate eggs. Beat the egg whites and 2 tablespoons of cold water with the whisk of the hand mixer until stiff, finally adding sugar, vanillin sugar and salt. Add egg yolks one after the other and fold in. Mix flour and baking powder, sieve onto the egg yolks and fold in.
Put the sponge mixture into a springform pan (approx. 26 cm Ø) greased and dusted with flour at the bottom only and smooth it down. Bake in the preheated oven, middle shelf (electric oven: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 20 minutes. Let the sponge cake cool down in the tin on a cake rack for about 1 hour.
Remove deep-frozen cream puffs from the package and allow to thaw for 15-20 minutes. Whip the cream until stiff in portions, allowing the preserving sugar to trickle in. Stir the sour cream until smooth, then fold in the cream.
Remove the sponge cake base from the springform pan, place it on a cake plate and place a cake ring around it. Spread about half of the cream on the cake base, cover with cream puffs. Spread the rest of the cream on top. Lightly push the cake onto the table top so that no cavities are formed. Chill for about 2 hours.
Drain the apricots in a sieve, collecting the juice. Cut the apricots into fine slices and cover the cake with them. Measure 250 ml + 3 tbsp. apricot juice. Mix the cake glaze with a little juice. Gradually stir in the remaining juice.
Bring the liquid to a boil while stirring. Bring to the boil briefly. Spread the glaze over the apricots with a tablespoon. Chill the cake for 3-4 hours. Roast the almonds in a pan without fat, take them out immediately and let them cool down. Remove the cake from the cake ring. Sprinkle the cake ring with flaked almonds.