If you don’t have an ice cream maker, freeze the mixture in a shallow, covered container for 1–2 hours. Mix well with a fork or a wide whisk, and then return to the freezer for 2–3 hours until just frozen. Thaw for a few minutes before topping and serving. For a creamier consistency, break up the slightly thawed ice cream into chunks, and pulse them in the food processor before topping and serving.