For the base, add fat, icing sugar, flour, egg yolk and baking powder to make a smooth short pastry. Cover and chill for about 30 minutes. In the meantime, wash, quarter and stone the plums for the compote.
Bring currant juice and sugar to the boil. Stir cornflour and about 3 tablespoons of water until smooth. Bind the juice with it and add the plums. Roll out the dough into a circle (26 cm Ø) on a floured work surface.
Prick several times with a fork and bake in the preheated oven (electric oven: 200 °C/ gas: level 3) for 15-20 minutes and let it cool down. Cover with the edge of the springform pan. Spread 3/4 of the compote lukewarm on top and let it get firm.
Soak gelatine for the cream. Stir yoghurt, mascarpone and sugar until smooth. Season with lemon juice and zest, cinnamon and vanilla flavouring. Squeeze out the gelatine, dissolve lukewarm and gradually stir into the cream.
Fold in Amaretti. Spread the cream on the compote and chill. Warm the rest of the compote lukewarm, adding 2 tablespoons of water if necessary. Carefully spread on the cake and let it cool down.
Before serving, decorate with amaretti, meringue and mint to taste. Makes about 12 pieces.