01 - Combine chopped dates with water in a small saucepan. Cook over medium heat for 5-7 minutes until dates soften into a thick paste. Stir in orange blossom water and lemon juice. Let cool completely.
02 - Beat chilled heavy cream in a mixing bowl until soft peaks form. 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 pinch of salt until foamy. Gradually add remaining sugar and continue beating until stiff glossy peaks form.
05 - Gently fold cooled date paste into the egg yolk mixture until fully incorporated.
06 - Fold whipped cream into date-yolk base. Gently incorporate beaten egg whites using light folding motions until mixture is smooth and airy. Avoid deflating the mixture.
07 - Spoon or pipe mousse into individual serving glasses or ramekins. Refrigerate for minimum 2 hours until completely set.
08 - Sprinkle chopped pistachios and orange zest over chilled mousse. Top with dried rose petals if desired. Serve immediately.