Peel and core the apples and slice into a saucepan. Add the washed blackberries, the water and
When the fruit is cooked, draw off the heat. Add the soaked gelatine and stir until dissolved – the heat of the pan will be sufficient to do this. Rub the fruit and juice through a sieve into a mixing basin to make a purée; discard any pips from the blackberries remaining in the sieve. Set the fruit purée aside until cold and beginning to thicken.
Quickly whisk the egg whites until stiff, add the remaining sugar and beat again just to blend. Fold into the fruit purée, pour the mixture into a serving dish and chill until set firm.