Begin by gathering your high-quality, unsalted, shelled pistachios. Using a food processor, blend the pistachios into a fine powder for about 1-2 minutes.

In a mixing bowl, beat the mascarpone until it reaches a smooth and creamy consistency. Then, gently fold in the freshly whipped cream.

Carefully add the ground pistachios and sugar to the mascarpone mixture. Use a spatula to fold everything together until uniform.

Spoon the pistachio mixture into individual serving glasses, cover with plastic wrap, and refrigerate for at least 4 hours or overnight.

Heat the heavy cream in a small saucepan until simmering, then pour it over the chopped chocolate in a heatproof bowl, stirring until smooth.

Pour the ganache over each glass of mousse once set, allowing it to cascade down the sides. Garnish with crushed pistachios or fresh mint.