You don't need an ice-cream maker (or a Pacojet) to make sweet and creamy frozen treats. The Italians have the answer and it's called semifreddo.
The Chinese are credited with inventing - among many other things - the first ice-cream maker, by packing large handfuls of snow and saltpetre (potassium nitrate) around a canister to freeze its contents. Since then, hand churns, domestic makers and electric jets that churn in a heartbeat have opened up a world of frozen treats. But for those who don't own an ice-cream maker or don't have access to buckets of snow and saltpetre, semifreddo (literally "semi-cold") is the answer.
While ice-cream uses many of the same ingredients as semifreddo - egg yolks, sugar, cream - the technique for making it is different. For ice-cream, you make a crème anglaise, or custard, by creaming the yolks and sugar, then combining them with hot cream (and milk). This is cooked slowly, gently and with constant stirring until it thickens; the mixture is then cooled and frozen in an ice-cream machine.
In contrast, semifreddo, which hails from Italy's Emilia-Romagna region, consists of a sabayon and a roughly equal quantity of whisked cream. Its mousse-like texture means it doesn't freeze as solidly as ice-cream. Semifreddo is typically presented as a frozen terrine, but it can just as easily be scooped as you would serve ice-cream.
Some recipes also call for eggwhite, which is whisked until stiff then folded through after the cream. It's especially good in a moulded semifreddo - whisked eggwhite adds more air to the mix, creating a frozen soufflé-like finish.
If you're using a mould, line it first with plastic wrap or baking paper, then place it in the freezer before making your sabayon. The lining will make it easier to turn your semifreddo out for slicing. (Semifreddo melts quickly if the mould is dipped in hot water because of the mousse-like texture.) Or scoop it out, as we've done here.
The next step is to prepare your sabayon, a cooked egg yolk mixture which is whisked in a bowl over a saucepan of simmering water to prevent the eggs from cooking too quickly. Whisking the eggs while cooking increases the volume of the mixture by adding air, and cooks the egg yolk, which helps to stabilise the semifreddo.
When the sabayon has tripled in volume, is thick and pale, and holds a ribbon, you need to cool it before adding your flavourings and the whisked cream. Cooling the mixture prevents the whisked cream from melting when it's added. To cool, you can place the sabayon over a bowl of iced water and whisk continuously until cooled, but it's much easier to place the mixture in an electric mixer which can do the work for you.
Once the sabayon is cooled, add your desired flavourings. These could be chocolate and hazelnut (like we've done here), or you could fold though some puréed fruit, or some spices.
Finally, fold through the cream. You can fold using a whisk which will incorporate the cream through the sabayon quickly and evenly, or you can use a plastic spatula, turning the bowl as you fold. Then pour it into your mould and freeze (overnight for best results).