Roughly chop the walnuts. Simmer maple syrup and 75 g sugar in a pan for 1-2 minutes (see fig. A). Stir in the nuts, except for 1 tbsp. and continue to simmer for approx. 1 minute. Spread thinly on a piece of baking paper and let it cool down.
Line an ovenproof dish (approx. 2.4 l capacity) with cling film. For the ice cream mass, cut the vanilla pod lengthwise and scrape out the pulp with a sharp knife. Crumble the cookies roughly.
Separate eggs. Beat egg whites and cream separately until stiff, cover and chill.
Whisk the egg yolks, vanilla pulp and 100 g sugar with the whisks of the mixer for 3-5 minutes until light creamy. First fold in crème fraîche, then cookies and nut caramel with a dough scraper. Then fold in cream and beaten egg white.
Immediately pour the ice cream mixture into the mould and smooth it down. Cover with cling film and freeze for 4-5 hours. The ice cream should be frozen through, but not hard.
Before serving, leave Semifreddo in the mould at room temperature for 10-15 minutes to thaw, then turn over and remove the foil. If necessary, allow Semifreddo to thaw for a further 10-15 minutes and portion, then refreeze the rest if necessary.
Sprinkle with the remaining nuts. Serve with chocolate sauce.