Put the nougat in the freezer for at least a couple of hours and then chop it finely with a blender.
Separate the egg whites from the yolks. In a bowl beat the egg whites with a pinch of salt and a pinch of powdered sugar, until they're stiff. In another bowl, beat the yolks with sugar. In a third bowl, whip the cream.
Now, mix everything together with a wooden spoon or a spatula, mixing from bottom up (being careful to not deflate the mixture); then add the chopped nougat and, if you want to, some rum (about a tablespoon).
Pour the mixture in single-portion cups (I used the disposable aluminum ones), cover them with aluminum foil and then put them in the freezer for at least 10 hours before serving them (but you could prepare this dessert even a week before, or more).
When you serve your semifreddi (plural), take them out of the mold on dishes and, if you want to, garnish them with a sauce made with melted chocolate and a drizzle of hot milk (to make your sauce more fluid), or with a ganache made with melted chocolate and piping hot whipping cream.