Cut the fat into small cubes. Mix flour with fat, 80 g sugar, 2 eggs, orange-back and salt to a smooth dough. Cover and put in a cool place for about 30 minutes. Roll out to a thickness of approx. 5 mm on a floured work surface. Grease a tart tin (approx. 28 cm Ø), dust with flour and line with the dough. Cut off the protruding edge of the dough and put the tin in a cool place.
Drain plums. Mix the sour cream with the remaining eggs, sugar and vanilla sugar until smooth. Spread the pastry base with plum puree. Spread plums on top. Pour the custard mixture over it and bake in a preheated oven (electric range: 200 °C/ gas: level 3)
Bake on the lower rack for about 1 hour. After about 40 minutes sprinkle with almonds. Take the tart out of the oven, let it cool down for about 20 minutes and lift it out of the tart mould. Dust with icing sugar and divide into about 16 pieces. Serve with whipped cream