400g/14oz fresh blackberries
1 lemon, peeled
1 orange, peeled
450g/1lb caster sugar
1 cinnamon stick
ΒΌ tsp ground cloves
1 tbsp cornflour
Β½ tsp ground ginger
1 tbsp vanilla bean paste
1 tbsp white wine vinegar
600ml/20fl oz double cream
6 free-range egg whites
50ml/2fl oz crème de cassis