Authentic Italian spumone is essentially an unmolded bombe, below, usually with a center of soft semifreddo or pastry cream, often flavored with amaretti cookies and studded with candied fruit.
Line a 9 × 5-inch loaf pan with plastic wrap, allowing the excess to hang over the edges. Spread evenly in the bottom of the pan:
Freeze until firm enough to hold the next layer, about 30 minutes.
Spread evenly on top of the first layer:
Freeze as for the first layer.
Beat together in a medium bowl:
Spread over the pistachio ice cream and freeze until hard, for at least 2 hours.
Unmold and remove the plastic wrap. Slice and serve with: