Start with the rocher base. Mixed together the melted chocolate, pistachios and apricots and pour into the base of a lined spring bottom cake tin. Even out and place into the fridge to set. Break up the marie biscuits and place into a large bowl. Allow the ice-cream to get soft, then pour into the bowl with the biscuits. Mix together and pour over the rocher base and even out. Place into the freezer for 4-5 hours to set. When ready, quickly melt together the 100ml fresh cream to form a smooth ganache and allow to cool down. Remove the semi-freddo from the freezer and place onto a cake stand. Pour over the cooled ganache and decorate the top with the extra chopped apricots and pistachios. Dredge with icing sugar and serve immediately.