Semifreddo

That's exactly how it's done: beat the egg yolks with sugar until pale and fluffy, whip the cream separately to stiff peaks, then fold together with a spatula using gentle folding motions. Pour into a plastic-wrap-lined loaf pan and freeze for at least 4 hours. No churning needed — the air whipped in beforehand creates the creamy texture on its own.

The cause is under-whipping. The cream must hold stiff peaks, and the yolks with sugar must become a pale, fluffy ribbon that has doubled in volume. If either component is underwhipped, there isn't enough air and the mixture freezes solid. Another common mistake is not wrapping the pan tightly, allowing moisture to form ice crystals on the surface.

All three work beautifully but in different ways. Berry puree (50–80 g of strawberries or raspberries) adds a bright sweet-tart flavor. Dark chocolate (50 g, melted and cooled) gives a rich, slightly bitter note. Crushed pistachios or hazelnuts add a crunch that contrasts with the soft texture. Fold any addition in at the very end using gentle strokes to keep the air in the mixture.

Ideally up to 7–10 days. Technically it keeps for up to 2 weeks, but after the first week small ice crystals start to form and the texture becomes less creamy. Wrap the pan tightly in two layers of plastic wrap right after freezing — this is the main protection against crystallization and absorbing freezer odors.

Yes. The easiest substitute for 4 yolks is 3–4 tablespoons of sweetened condensed milk — it provides similar fat content and sweetness. The second option is to increase the cream to 350 ml and add 1 tablespoon of powdered sugar. In both cases the dessert will work, though it will be slightly less stable when sliced.