01 - Combine chopped dates and water in a small saucepan. Cook over low heat for 3-4 minutes, stirring constantly until softened and jammy. Remove from heat and allow to cool completely.
02 - In a chilled bowl, whip cold heavy cream using an electric mixer or whisk until soft peaks form. Refrigerate immediately to maintain structure.
03 - Whisk egg yolks and granulated sugar in a separate bowl until pale, thick, and doubled in volume. Incorporate orange blossom water and lemon zest until fully combined.
04 - Process cooled date mixture in a food processor or blender until completely smooth. Fold the date paste into the yolk mixture until uniform.
05 - Gently fold whipped cream into the date-yolk mixture in two additions, using a spatula with light, lifting motions to maintain airiness.
06 - In a clean, grease-free bowl, whisk egg whites to stiff peaks. Carefully fold into the mousse base using minimal strokes to preserve volume.
07 - Distribute the mousse evenly among individual serving glasses or bowls, tapping gently to release any air pockets.
08 - Refrigerate for a minimum of 2 hours or until completely set and firm to the touch.
09 - Just before serving, sprinkle with chopped pistachios, fresh orange zest, and sliced dates if desired.