Chocolate Truffle Rods
Chop both chocolates and place into a bowl. Boil the cream, pour over the chopped chocolate and let melt, while gently stirring. Gradually stir in the Cognac. Allow the mixture to cool for at least 5 hours. Cut the butter into small pieces and gradually fold into the chocolate cream.
Place into a piping bag with a large round tip and pipe about 8 cm (approximately 3 inch) long rods (about 1.5 cm thick) (approximately 1 inch) onto parchment paper. Chill for at least 1 hour. Melt the dark chocolate, let cool until lukewarm, and coat the truffle rods. Let drip off and then make striations with a fine tip, if desired. Allow to dry and serve dusted with cocoa.