01 -
Process pistachios and sugar in a food processor until a smooth thick paste forms, scraping down the sides as needed.
02 -
Beat chilled heavy cream until soft peaks develop, then incorporate vanilla extract and optional almond extract with a brief mix.
03 -
Lighten pistachio paste with a small amount of whipped cream, then gently fold into the remaining cream to preserve airiness.
04 -
Divide mousse evenly into 4 to 6 serving glasses and refrigerate for 1 to 2 hours to set.
05 -
Heat heavy cream until steaming, pour over chocolate chips, let rest for 1 to 2 minutes, then stir until smooth and glossy.
06 -
Allow ganache to cool slightly before pouring over chilled mousse. Chill for at least 1 hour to firm up.
07 -
Top the assembled dessert with chopped pistachios, shaved chocolate, or a dollop of whipped cream. Serve chilled.