Bring first 3 ingredients to boil in small saucepan, stirring until sugar dissolves. Reduce heat to medium-low; simmer until reduced to thin syrup, about 5 minutes. Pour into 8x8x2-inch glass baking dish. Stir in remaining ingredients. Cover; freeze overnight.
Using fork, scrape granita in its dish into flakes. Cover and keep frozen up to 2 days.
