
Put the Prosecco, Aperol and water in a bowl then add the sugar. Stir until the sugar has dissolved.
Pour the mixture into a large freezer-safe container so the mixture is only 1-2 inches deep.
Put the container into the freezer. After 1 hour remove it from the freezer and stir it with a fork. Put it back into the freezer and continue stirring it gently every 30 minutes to an hour for about 4 hours until the granita has formed (You should be able to see the ice crystals forming and getting larger each time you stir it).
Best eaten within 2-3 days (flavour-wise) but will keep in the freezer for months.