Cassata can be either fruit-filled ice cream, as it is here, or a rich layer cake with ricotta cheese, fruit, chocolate, and cream.
- Combine rum, liqueur, and candied fruit in a small bowl; set aside for at least half an hour.
- Meanwhile, line a 2-quart loaf pan or mold with a large piece of plastic wrap, pressing it well into the corners. In a medium bowl, whip the cream to soft peaks.
- Spoon softened ice cream into a large bowl; fold in rum-fruit mixture, pistachio nuts, and chocolate. Gently fold in whipped cream.
- Pour into plastic-lined pan. Tap the pan against a cutting board several times to fill the corners. Cover with plastic wrap and freeze overnight.
- To serve, invert the pan on a chilled platter. Lift off the pan and remove the plastic wrap. Garnish cassata with whipped cream rosettes, candied cherries, or a light dusting of cocoa (if desired). Cut into slices.