You will need
Whip egg whites until beginning to thicken. Beat in sugar, then cream, water and 150ml/5fl oz champagne.
Pour into ice cream maker and churn or into a freezer-proof bowl and freeze.
As mixture begins to freeze, remove bowl, beat to break down ice crystals and return to freezer.
After about 30 minutes, remove and beat again. Return to freezer.
When completely frozen serve drizzled with remaining champagne.