Defrost the raspberries. Grease a springform pan (18 cm Ø) only at the bottom and dust with flour. Preheat the oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer).
Separate the eggs for the sponge cake. Beat the egg whites with 2 tablespoons of cold water until stiff, adding sugar and 1 pinch of salt at the end. Continue beating until the sugar has dissolved. Stir in egg yolk.
Mix 30 g flour, starch and baking powder, sieve onto the egg foam and carefully fold in. Smooth the sponge cake mixture in the mould. Bake in a hot oven for 15-20 minutes. Take out and let cool down for about 15 minutes.
Remove from the mould and let it cool down.
For the filling raspberries, up to about 5 pieces for decoration, puree 2 tablespoons icing sugar and vanilla sugar with a hand blender. Put approx. 2 tbsp. puree aside. Stir ricotta and 30 g icing sugar until smooth.
Whip cream until stiff and fold in.
Cut the biscuit twice horizontally. 1⁄3 Spread the cream on the lower base. 1⁄2 Spread raspberry puree on top. Carefully place the middle base on top. Spread 1/3 of the cream and the rest of the puree on top. Carefully place the top cake layer on top.
Spread the rest of the cream loosely over the top. Decorate with 2 tablespoons of puree and the rest of the berries. Chill for at least 30 minutes. Dust the cheesecake with icing sugar.