- STIR crumbs with 2 tbsp cream in a medium bowl until combined but still crumbly. For easier removal of cake, flip base of 9-in. springform pan upside down. Line base with foil, then clamp side band. Press crumbs onto foil in an even layer.
- PLACE chocolate in a large microwave-safe bowl. Heat on medium until almost melted, stirring halfway through, about 3 min. Remove and stir until completely melted. Set aside.
- BEAT 6 egg whites with salt in a medium bowl using an electric mixer on high until soft peaks form when beaters are lifted, about 2 min. Using the same beaters (no need to wash them), in a large bowl, beat 1 cup cream on high, gradually adding 1/4 cup sugar, then 1 tsp vanilla, until soft peaks form, about 2 min. Fold egg whites into cream just until mixed. Stir one-third of cream mixture into cooled chocolate mixture. Fold in remaining cream mixture until no white streaks remain. Scrape over cookie crust and smooth top. Freeze until firm, about 3 hours.
- STIR together 1/2 cup sugar, 1/2 tsp vanilla and 3 tbsp water in a small saucepan over medium-high. Bring to a boil and let boil without stirring for 1 min. Remove from heat. Whip 2 egg whites in a large bowl on high until soft peaks form when beaters are lifted, about 1 min. Gradually pour hot syr- up into the bowl, beating whites until stiff peaks form, 4 to 5 min. Frost the top of the frozen cake to the edges, making decorative peaks. Sprinkle with toasted almonds.
Use pasteurized egg white for mousse (3/4 cup) if desired, but not for meringue — it won’t stiffen as well.
Lightly cooked egg whites are generally safe to eat but may pose a risk to young children, pregnant women, the elderly or anyone with a compromised immune system.