- 1 cup low-fat milk
- 1/2 cup sugar
- 2 teaspoons plain powdered gelatin
- 2 tablespoons cold water
- 1/3 cup fat-free sour cream (3 ounces)
- 1 1/2 cups plain fat-free Greek yogurt
- 2 tablespoons fresh lime juice
- 1/4 teaspoon pure vanilla extract
- 3 tablespoons water
- 3 tablespoons sugar
- 1 pineapple (1 3/4 pounds)—peeled, cored and quartered
- Pinch of salt
- In a large saucepan, heat the milk with the sugar over low heat, stirring, until the sugar is dissolved. Meanwhile, in a small bowl, sprinkle the gelatin over the water and let stand until softened, 3 minutes. Scrape the gelatin into the warm milk and let cool completely.
- In a medium bowl, whisk the sour cream with the yogurt, lime juice and vanilla. Whisk in the milk and pour the panna cotta into 6 glasses. Refrigerate until set, 3 hours.
- In a saucepan, cook the water and sugar over moderate heat, stirring, just until the sugar is dissolved. Let cool completely.
- Cut three-fourths of the pineapple into chunks, transfer to a blender and puree; strain into the saucepan with the sugar syrup, pressing hard on the solids. Discard the pulp. Stir the salt into the pineapple puree and pour it into a 9-by-13-inch baking dish. Freeze for 30 minutes. Using a fork, stir the granita. Continue freezing, stirring every 30 minutes, until the granita is icy and fluffy, about 3 hours.
- Cut the remaining pineapple into thin slices. Fluff the granita with a fork and spoon it over the panna cottas. Garnish with the pineapple slices and serve right away.
The panna cottas can be covered and refrigerated for up to 4 days. The granita can be frozen in an airtight container for up to 4 days. Fluff before serving.