Place first 5 ingredients in a blender; process until smooth. Pour into an 8-inch square glass or ceramic baking dish. Cover and freeze until partially frozen (about 2 hours). Scrape with a fork, crushing any lumps. Freeze 1 hour or until completely frozen; scrape entire mixture with a fork until fluffy. Divide ice among 7 dishes, and top each serving with 1 teaspoon coconut, if desired.