Sift flour and salt into a bowl and mix in the sugar.
Add butter and mix together in the Robot Coupe to resemble breadcrumbs.
Add the egg mixture and pulse for a few seconds until mixture comes together.
Put onto floured surface and knead for a minute until smooth. Wrap in cling film and refrigerate for at least 30 minutes.
Beat the butter and the sugar together until pale and creamy.
Incorporate the egg and then add the almonds
Dissolve the sugar in the water and simmer for 5 minutes then leave to cool slightly.
Halve 8 of the plums, remove stones and cut into thin wedges.
Place in a saucepan and cover with stock syrup. Gently poach for 6-8 minutes until soft, but do not over cook.
Carefully remove from stock and allow to cool. Keep the stock.
Chop the other 4 plums and poach in the reserved stock for about 10 minutes. Remove the plums from the stock and blend until smooth with a couple of tbsp of the syrup to get to the correct consistency.