Nutrition: per serving
Whizz the raspberries and icing sugar together in a food processor, then sieve, pressing through as much raspberry as you can with a wooden spoon. Line a 2lb loaf tin with cling film – it helps if you brush the tin with oil first to get the cling film to stick and stay in place. Pour in the raspberry sauce and freeze for 1 hr.
Quickly dip the nougat bars in water – this should allow you to peel away the rice paper; don’t worry if you don’t get it all as it will disappear when melted. Put the bars into a pan with 200ml cream. Melt over a low heat, stirring constantly and using a wooden spoon to break up the nougat into smaller bits as it softens. After a while you should end up with a smooth, sticky, creamy mixture. Remove from the heat and set aside to cool a little. Whip the remaining cream in a large mixing bowl to stiff peaks.
When the nougat is cooler, but still soft and sauce-like, fold it one-third at a time into the whipped cream. Scatter over the whole nuts and fold once to mix. Scrape into the loaf tin, cover with cling film and freeze overnight, or for up to a month.
Transfer the loaf to the fridge 15 mins before you want to serve it. Unwrap and turn out onto a serving plate. Peel off the cling film, roughly chop a few extra pistachios and scatter over before slicing.