Mix flour, icing sugar, ground nuts and baking powder. Add butter and egg yolks, first with the dough hooks of the hand mixer, then knead with your hands to a smooth dough. Grease 6 tartlet cups (10 cm Ø) and dust with flour. Divide the dough into 6 portions and press into the moulds. Chill for about 1 hour.
Bake in the preheated oven (electric cooker: 200°C/ convection oven: 175°C/ gas: level 3) for 15-20 minutes. Allow to cool a little, turn out of the ramekins and let them cool down. Mix mascarpone, quark, vanillin sugar and 25 g sugar. Wash the grapes, drain them, cut some in half. Spread the cream on the tartlets, add the grapes. Mix the cake glaze and 25 g sugar, stir gradually with wine until smooth. Bring to the boil briefly while stirring. Spread the glaze on the grapes with a tablespoon. Chill for 30 minutes.
Spread the cream on the tartlets, add the grapes. Mix the cake glaze and 25 g sugar, stir gradually with wine until smooth. Bring to the boil briefly while stirring. Spread the glaze on the grapes with a tablespoon. Chill for 30 minutes. Chop the nuts and sprinkle over them
waiting time approx. 2 hours