Beat the fat, icing sugar and vanillin sugar with the whisk of the hand mixer until foamy. Stir in the eggs one after the other. Mix flour, cornstarch, baking powder and cocoa. Sift over it and stir in. Line the muffin tin (12 troughs) with paper sleeves. Fill in dough evenly.
Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for about 30 minutes. Mix grappa and coffee, drizzle on the muffins and let cool. For the filling, mix mascarpone, quark, sugar, lemon juice and flavour until smooth. Wash the grapes and pluck them from the stems. Spread the cream on the muffins. Place the grapes on the cream and serve
Waiting time approx. 30 minutes