Place a small glass or metal bowl over a small pot with about 2 inches of water in it. Bring to boil.
Place chocolate in bowl and stir until melted. Remove bowl from top of pot and allow to cool slightly
In a separate bowl, beat 2 egg yolks and 3 tablespoons sugar until egg yolks double in size. Stir in Pisco.
In another bowl whip 2 cups heavy cream with 2 tablespoons sugar and 1/2 teaspoon vanilla. Set aside 3/4 cup whipped cream for topping.
Carefully beat together chocolate and egg yolk mixture by pouring egg yolk slowly into bowl with chocolate with beaters running. Be careful not to cook the eggs.
Add several heaping spoonfuls of whipped cream to egg chocolate mixture and beat on low until combined.
Fold in remaining whipped cream.
Pour mousse into desire containers or bowls and refrigerate for at least 2 hours.
Top with whipped cream.