- blackberries - 450 g, (1 lb), fresh or frozen, thawed,
- egg whites - 2,
- caster sugar - 50 g (2 oz),
- double cream - 300 ml.
- Purée the blackberries and rub through a nylon sieve.
- Pour the purée into a rigid container and freeze for about 2 hours.
- Whisk the egg whites until stiff, then add the Sugar gradually, whisking until the mixture stands in soft peaks.
- Whip the cream until it just holds its shape.
- Remove the frozen blackberry purée from the freezer and mash to break down any large ice crystals, being careful not to break it down completely.
- Fold the cream and egg whites together, then quickly fold in the semi-frozen blackberry puree to form a swirled effect.
- Spoon into tall glasses and serve immediately.