- 2 cups fresh ruby red or pink grapefruit juice, divided
- 6 tablespoons sugar
- 2/3 cup Campari
- 1 tablespoon (packed) finely grated ruby red or pink grapefruit peel
- 4 ruby red or pink grapefruits
- 1 cup chilled heavy whipping cream
- 1/4 cup chilled crème fraîche or sour cream
- 4 teaspoons powdered sugar
- 1 1 1/2-inch piece vanilla bean, split lengthwise
- Combine 1 cup grapefruit juice and sugar in medium saucepan. Stir over medium heat until sugar dissolves. Increase heat and bring to boil. Remove from heat; stir in remaining 1 cup grapefruit juice, Campari, and grated peel. Pour mixture into 11x7x2-inch glass baking dish or metal baking pan. Cover and freeze until firm, at least 8 hours or overnight. DO AHEAD: Can be made 3 days ahead. Keep frozen.
- Using sharp knife, cut off all peel and white pith from 4 grapefruits. Working over bowl to catch juices and using small sharp knife, cut between membranes to release segments into bowl. Squeeze any remaining juice from membranes into bowl. DO AHEAD: Can be made 4 hours ahead. Cover; chill.
- Combine whipping cream, crème fraîche, and powdered sugar in medium bowl. Scrape in seeds from vanilla bean; reserve bean. Using electric mixer, beat mixture until soft peaks form. Add reserved vanilla bean to cream mixture; cover and chill at least 2 hours. DO AHEAD: Can be made 4 hours ahead. Keep chilled.Remove vanilla bean and rewhisk cream mixture until thick before using.
- Using fork, scrape surface of granita to form icy flakes. Divide grapefruit segments and juices from bowl among 6 dessert glasses. Divide granita among glasses. Top each with large dollop of vanilla whipped cream and serve immediately.