01 - Combine chopped dates with water in a small saucepan. Cook over medium heat for 5-7 minutes until dates are soft and mixture forms a thick paste. Stir in orange blossom water and lemon juice. Allow to cool completely.
02 - In a mixing bowl, whip the chilled heavy cream to soft peaks. Refrigerate until ready to use.
03 - Beat egg yolks with half the sugar and vanilla extract in a separate bowl until mixture becomes pale and thick.
04 - In a clean bowl, whisk egg whites with a pinch of salt until foamy. Gradually add remaining sugar and continue beating until stiff peaks form.
05 - Gently fold the cooled date paste into the egg yolk mixture until well incorporated.
06 - Fold the whipped cream into the date-yolk mixture. Then gently fold in the egg whites until the mousse achieves a smooth, airy consistency.
07 - Spoon the mousse mixture into individual serving glasses. Refrigerate for at least 2 hours until completely set.
08 - Just before serving, top each mousse with chopped pistachios, orange zest, and dried rose petals if desired.