To quickly chill, place bowl with yogurt mixture into a larger bowl. Fill that bowl with ice water to come halfway up the sides. Let stand until mixture is chilled, stirring occasionally, about 15 minutes.
- 1/4 cup juice and zest from 1 navel orange, plus more zest for garnish (optional)
- 1 1/2 cups heavy cream
- 3/4 cup sugar
- 1/8 teaspoon salt
- 1 (1/4 ounce) packet unflavored gelatin
- 1 container (32 ounces) plain low-fat yogurt
- 1/4 cup pistachios, chopped
In a saucepan, combine orange zest, 1/2 cup cream, sugar, and salt over medium heat. Bring to a simmer, stirring occasionally, until sugar has dissolved, about 5 minutes. Remove from heat, cover, and let steep 20 minutes.
Pour orange juice into a medium bowl; sprinkle with gelatin and let soften, 5 minutes. Bring cream and sugar mixture to a simmer again; pour through a fine-mesh sieve onto gelatin, pressing on zest to extract flavor. Discard zest. Whisk until gelatin has dissolved, about 1 minute. Gradually whisk in yogurt. Cover and refrigerate 30 minutes, or use quick-chill method.
In a medium bowl, with an electric mixer, beat remaining 1 cup cream until soft peaks form. Fold gently into yogurt mixture. Divide among 6 glasses, and cover each with plastic wrap; refrigerate at least 6 hours or overnight. To serve, sprinkle with pistachios and, if desired, orange zest.