Beat the egg yolks together with half the sugar in a food processor until light and airy, and set aside.
Beat the cream plus mascarpone in the food processor until light and airy, add the pistachio paste, and mix well.
Fold into the beaten egg yolks.
Beat the egg whites in the food processor until light and airy, and add the other half of the sugar.
Fold the egg white mixture into the mascarpone mixture.
Pour into a piping bag.