Blend all ingredients in a high speed food processor or blender.
If desired, mix in crushed pistachios by hand once the mixture is thoroughly blended.
Pour this into a shallow bowl and set in the freezer for about 3 hours, checking every hour until it reaches a soft serve consistency. Leaving it for longer will harden it up even more for a more ice-cream like texture versus soft serve.
When serving, if it's hard then allow it to thaw at room temperature, so it's easier to scoop with an ice cream scooper. You can run the ice cream scooper under boiling hot water to make it easier to scoop if needed.
Notes
Storage
Store in an airtight, freezer-safe container in the freezer for up to one week. If the ice cream becomes too hard, let it soften at room temperature for a few minutes before serving.