For the tart case, sweet pastry:
200g unsalted butter, softened
85g icing sugar
250g strong flour
1/2 tsp vanilla extract
1tsp salt
1 egg yolk
For the tart filling:
200g butter
200g sugar
4 eggs
40g flour
160g ground almonds
1tsp baking powder
4 plums
50g apricot jam
Zest of half a lemon