1. Combine condensed milk, milk, water, and butter in a bowl and beat until frothy.
2. Place in freezer and let sit for 1 hour.
3. Remove from freezer, stir, and return to freezer.
4. Let freeze overnight.
5. Remove from freezer, combine with mashed berries, and process in a blender until smooth.
6. Return to freezer and freeze for at least another 5 hours.
7. Enjoy!