Double-Chocolate and Orange Semifreddo

Semifreddo, which means “half cold” in Italian, is a creamy frozen dessert that lies somewhere between soft-serve ice cream and regular hard ice cream. It has the same ingredients as ice cream, but does not rely on an ice-cream maker to churn in air and freeze it. Instead, you beat air into the ingredients beforehand and place the confection directly into the freezer—no churning necessary. It then freezes into a soft dessert that you can scoop or slice. The first time I made semif