Grease the bottom of a springform pan (26 cm Ø). Cream 100 g butter, 100 g sugar and 1 pinch of salt. Mix 100 g flour, mixed almonds and 1 tsp. baking powder. Knead with the fat-sugar mixture and possibly 1 tbsp. water.
Press the dough into the mould . Bake in the preheated oven (175 °C/circulating air: 150 °C/gas: level 2) for 15-20 minutes. Allow to cool slightly, remove from the mould and allow to cool completely.
Clean the mould and line the bottom with baking paper. Beat the eggs, 2 tablespoons lukewarm water, 100 g sugar and 1 vanilla sugar for 6-8 minutes with a hand mixer until frothy. Sieve 75 g flour, starch and 1 tsp. baking powder on top and fold in with a whisk.
Smooth into the tin and bake at the same temperature for about 20 minutes. Remove the sponge cake from the tin and let it cool down.
Roast the flaked almonds and 1 tbsp. sugar in a pan without fat until golden brown. Add 1 tablespoon butter, remove from heat and let it melt. Stir almonds and let them cool down. Wash the grapes and pluck from the panicles.
Put some green and blue grapes aside for decoration. Whip the cream until stiff, if necessary in portions, while pouring in the cream thickener and 4 vanilla sugars.
Spread the kneaded pastry base with 1/4 cream. Spread blue grapes evenly on top. Carefully press something into the cream. Place the sponge cake on top. Spread with 1/4 cream. Arrange the green grapes on top and press them down lightly as well.
Spread the remaining cream on the cake. Press the flaked almonds onto the edge of the cake with your hands or a pastry sheet. Halve the rest of the grapes and decorate the cake with them.