4 poached pears or 2 x 400g tins pear halves in syrup, cut into large pieces
375g/13oz caster sugar
1 tsp cornflour
50g/2oz toasted hazelnuts, halved
50g/2oz icing sugar, sieved
1 tsp vanilla extract
1 tsp white wine vinegar
75g/3oz dark chocolate, broken into pieces
300ml/10fl oz double cream
6 large free-range egg whites
300ml/10fl oz Greek-style yoghurt