Wash and drain the grapes. Then pluck them from the stems, cut them in half and remove large seeds. Mix flour, baking powder, sugar, vanillin sugar and salt. Add oil, mineral water, eggs and rum flavouring.
Mix everything to a smooth dough with the dough hooks of the hand mixer. Grease the fat pan of the oven. Spread the dough evenly over it, spread grapes over it. Bake in the preheated oven (electric oven: 200 °C/ gas: level 3) for 30-40 minutes.
Results in about 24 pieces.