3 lemons, juice and zest
175g/6oz plain flour
150驳/5陆辞锄 caster sugar
25g/1oz icing sugar
icing sugar, for dusting
100g/3陆oz plain chocolate (36% cocoa solids), chopped
100g/3陆oz cold butter, cut into small cubes
100ml/3陆fl oz double cream
4 large free-range eggs
1 free-range egg yolk