Line a 28cm/11 inch loose-bottomed flan tin with the pastry and bake it
blind.
In a food processor, blitz the whole almonds to a fine powder and
put into a bowl. Then blitz the butter and sugar until light and creamy. Add
this to the almonds with the lightly beaten eggs and fold in until completely
mixed and nice and smooth. Stir in the pistachio nuts, then place in the fridge
to firm up slightly. Once the mixture has chilled, pour it into your tart case
about three-quarters full. You don’t want to overfill it otherwise it will spill
over the edge when you add the plums.
Toss the plums in the vanilla
sugar, let them sit for 10 minutes, then push them into the tart mixture. Bake
the tart on a tray at 180°C/350°F/gas 4 for about 1 hour, or until the almond
mix has become firm and golden on the outside but is still soft in the middle.
Allow to cool for about ½ an hour and serve with ice cream or crème
fraîche.