Orange-Pistachio Divinity

Directions

1. Place egg whites in bowl of a stand mixer; let stand at room temperature 30 minutes. Meanwhile, line two 15x10x1-in. pans with waxed paper.
2. In a large heavy saucepan, combine sugar, corn syrup and water; cook and stir until sugar is dissolved and mixture comes to a boil. Cook, without stirring, over medium heat until a thermometer reads 252° (hard-ball stage). Just before that temperature is reached, beat egg whites on medium speed until stiff peaks form.
3. With mixer continuing to run on high speed, slowly add hot sugar mixture in a thin stream over egg whites, beating constantly and scraping sides of bowl occasionally. Add orange zest and vanilla. Beat until candy holds its shape and begins to lose its gloss, 5-6 minutes. (Do not overbeat, or candy will stiffen and crumble.) Immediately fold in pistachios.
4. Quickly drop mixture by tablespoonfuls onto prepared pans. Let stand at room temperature until dry to the touch. Store between layers of waxed paper in an airtight container at room temperature.