4 cups fresh or frozen blackberries, thawed
In a food processor, combine blackberries and sugar; cover and process until smooth. Strain and discard seeds and pulp. Stir in buttermilk. Transfer puree to a 13-inch x 9-inch dish. Freeze for 1 hour or until edges begin to firm. Stir and return to freezer. Freeze 2 hours longer or until firm. Or freeze in your ice cream maker according to mfg. directions.
Just before serving, transfer to a food processor; cover and process for 2-3 minute or until smooth. This step not necessary if using ice cream maker.