01 - Combine chopped dates with water in a small saucepan. Cook over low heat for 3-4 minutes, stirring constantly until dates soften into a jam-like consistency. Remove from heat and let cool completely to room temperature.
02 - In a chilled large bowl, whip cold heavy cream using an electric mixer or whisk until soft peaks form. Refrigerate immediately to maintain structure.
03 - Whisk egg yolks with granulated sugar in a separate bowl until mixture becomes pale and thickened, approximately 3-4 minutes. Incorporate orange blossom water and lemon zest until fully combined.
04 - Process cooled date mixture in a food processor or blender until completely smooth. Gently fold date paste into yolk mixture until uniform color and texture achieved.
05 - Fold refrigerated whipped cream into date-yolk base in two separate additions, using gentle folding motions to maintain airiness and prevent deflation.
06 - Whisk egg whites in a clean, grease-free bowl until stiff glossy peaks form. Gently fold whites into mousse base using light, careful strokes to preserve maximum air volume.
07 - Divide mousse evenly among individual serving glasses or bowls. Refrigerate for minimum 2 hours until completely set and firm.
08 - Top chilled mousse with chopped pistachios, finely grated orange zest, and additional sliced dates. Serve immediately while cold.