1 x 360g/12陆oz jar black cherries in kirsch
陆 tsp arrowroot or cornflour mixed with a little water to make a smooth paste
175g/6oz caster sugar
2 tbsp cocoa powder
200g/7oz self-raising flour
100驳/3陆辞锄 dark chocolate (minimum 70% cocoa solids), melted, plus extra to serve
125驳/4陆辞锄 butter, softened
300ml/10fl oz double cream, lightly whipped
2 free-range eggs
125ml/4fl oz milk