- 4 cups water
- 4 cups caster sugar
- 1 (750 milliliter) bottle Champagne
- Combine water and sugar in a heavy bottom pot. Boil until reduced to a thin syrup, about 1 hour.
- Pour syrup into a heat-proof bowl and let cool to room temperature, about 2 hours.
- Pour Champagne into the syrup and mix until fully combined. Transfer mixture to an ice cream churner. Churn per manufacturer's directions until icy and no longer runny, about 35 minutes.