1 vanilla pod
150 grams caster sugar, divided
200 grams mascarpone
200 grams crème fraîche
¼ cup roughly chopped, chocolate coated nuts or coffee beans
Separate the eggs and place the yolks and egg whites in separate bowls.
Halve the vanilla bean and scrape out the seeds with the tip of a knife. Add to the yolks with 100 grams of the caster sugar. Beat until very thick and pale.
Beat the egg whites with the remaining 50 grams of caster sugar to stiff peaks.
Combine the mascarpone and crème fraîche in a large bowl. Using a large metal spoon, fold in the egg yolk mixture then fold in the egg whites. Pour the mixture into a freezer-proof container. Cover and freeze for at least 8 hours or preferably overnight.
To serve: Using an ice-cream scoop dipped in warm water, roll balls of semifreddo and place in chilled serving glasses. Top with the roughly chopped chocolate nuts. Serve immediately.
To simplify serving, roll the semifreddo ahead of time and place on a tray in the freezer.