If you don't have an ice cream maker you can turn the mix into a granita. Pour the mix into a flat metal pan, like a 13x9 brownie pan. Place the pan in the freezer for 30 minutes. Use a fork to stir the mixture and scrape any ice that formed around the edges of the mix. Repeat every 30 minutes for 3-4 hours until you have a fluffy, scoopable texture made up of small ice crystals.