For the short pastry, put flour, baking powder, sugar, salt, 1 packet of vanilla sugar, 1 egg and butter in flakes in a mixing bowl and knead into a smooth dough using the dough hooks of the hand mixer. Knead again with your hands. Cover and chill for approx. 30 minutes. In the meantime, wash the grapes, drain well and remove from the panicles. Coarsely grate the marzipan and gradually add 4 eggs with the whisk of the hand mixer. Stir in 1 packet of vanilla sugar, sour cream and sauce powder one after the other. Roll out the dough on a floured work surface to a circle (32 cm Ø), place it in a well greased form (Lift-Off-Form 28 cm Ø), press the rim and prick the base several times with a fork.
Sprinkle with ground almonds. Spread grapes on top and pour the sour-marzipan glaze over it. Sprinkle with almond slivers. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 45 minutes on the bottom shelf. Remove from the oven and let it cool down on a grid. Remove from the mould and sprinkle the rim with icing sugar. Whipped cream tastes good with it
waiting time approx. 2 hours