Chop both couvertures and melt them with coconut oil in a hot water bath. Mix eggs, icing sugar and cocoa with the whisk of the mixer until light creamy. Stir in the melted couverture mixture in a thin stream.
Keep the mixture warm in a water bath.
Line the box form (approx. 25 cm long; 1 1⁄2 l capacity) with foil. Spread some chocolate cream on the bottom of the mould. Break the biscuits into pieces and meringue roughly. Spread parts of each of the biscuits, meringue, cranberries and pistachios as a layer on the cream.
Then pour a thin layer of chocolate cream on top. Repeat until the chocolate cream, biscuits, meringue, pistachios and cranberries are used up. Chill for at least 5 hours, preferably overnight.