Whip the cream in a bowl until it forms soft peaks, then refrigerate.
Beat the egg yolks in a planetary mixer. In the meantime, make a syrup with water and sugar in a small saucepan and cook it until it reaches a temperature of 121°C.
Trickle it into the egg yolks, lowering the speed, and continue to whisk until the mixture has reached room temperature (pâte à bombe).
Melt the chocolate in the microwave on maximum power, checking its condition every 50–60 seconds and stirring with a spoon until completely melted. Incorporate a quarter of the cream into the hot chocolate, at which point the mixture will thicken slightly, then stir until glossy and elastic. Now fold it gently into the pâte à bombe using a spatula.
When the mixture is smooth and shiny, add the semi-whipped cream in 2–3 steps, folding it in from the bottom up. Transfer the mixture to a 11 x 30 cm rectangular cake mould lined with cling film and freeze for at least 6 hours.
Just before serving, take the semifreddo out of the freezer, cut it into slices and serve them with Fabbri Top Caramel and Maldon salt to taste.