Plum Semifreddo

Preparation

1. Step 1

   Coat a 9x5" loaf pan with nonstick spray and line with plastic wrap, leaving a generous overhang on all sides.

   Step 2

   Combine plums, cardamom, 1/3 cup sugar, and a pinch of salt in a medium saucepan. Cover and cook over medium heat, stirring occasionally, until plums release their juices, about 5 minutes. Uncover and cook until plums soften and start to fall apart, 6-8 minutes longer. Let cool slightly.

   Step 3

   Purée plum mixture in a blender until very smooth. Strain through a fine-mesh sieve into a medium bowl, pressing on solids. Let cool. Set aside 1 cup purée for serving.

   Step 4

   Whisk egg whites, a pinch of salt, and remaining 2/3 cup sugar in a medium heatproof bowl (or the bowl of a stand mixer) and set over a saucepan of simmering water (do not let bowl touch water). Heat, whisking constantly, until sugar is dissolved and mixture is warm to the touch, about 4 minutes. Remove bowl from saucepan. Add vanilla and, using an electric mixer on high speed, beat until mixture is tripled in volume, glossy, and completely cool, about 10 minutes.

   Step 5

   Using clean beaters, whip cream in another medium bowl until soft peaks form. Fold 1/3 of whipped cream into eggwhite mixture until just combined. Fold in remaining whipped cream until just combined. Fold in plum purée just until large streaks appear throughout mixture.

   Step 6

   Transfer mixture to prepared pan and smooth top. Fold plastic wrap overhang over top and freeze until firm, at least 8 hours.

   Step 7

   Unwrap semifreddo and, using plastic overhang, gently lift from pan. Invert semifreddo onto a large platter, remove plastic wrap, and slice 1" thick; transfer to plates and let sit at least 5 minutes to soften slightly. Serve with reserved plum purée.

   Step 8

   DO AHEAD: Plum purée can be made 3 days ahead. Cover and chill. Semifreddo can be made 3 days ahead. Keep frozen.