Make the coffee, melt the chocolate and let both cool down to room temperature.
Separate eggs whites from yolks. Whip egg whites until they form peaks and gradually add half the sugar. Keep whipping until well combined.
In another bowl, whip butter into a soft cream, adding the rest of the sugar, eggs yolks, vanilla extract and melted chocolate until mix is smooth. Delicately fold the egg whites.
Meanwhile, line a baking tray with cling film. Dip each biscuit into the coffee and arrange in a baking tray, forming a layer of biscuits. Cover with ¼ of the chocolate cream.
Proceed again, alternating between a layer of biscuits and a layer of cream, finishing with the cream on top.
Put in the fridge for a minimum of 12 hours (24, or even 48 hours, is better). Pulling the cling film, remove from the tin and decorate with chocolate sprinkles.