Baby pineapples that have been hollowed out make beautiful serving shells for this granita. These pineapples are available at specialty produce markets.
In a saucepan bring sugar and water to a boil, stirring until sugar is dissolved, and cool syrup.
In a blender or food processor purée pineapple with 1/4 cup plus
2 tablespoons syrup (reserving remaining syrup for another use). Stir in nectar or juice and Champagne. Pineapple mixture may be made 1 day ahead and chilled, covered.
Transfer pineapple mixture to a shallow metal baking pan and freeze, stirring and crushing lumps with a fork every hour, until mixture is firm but not frozen hard, about 3 to 4 hours. Granita may be made 2 days ahead and frozen, covered. Just before serving, scrape granita with a fork to lighten texture.
