Break half of the dark chocolate into small pieces into a small, heatproof bowl.
When the kettle has boiled, pour the water into a small saucepan to a depth of around 1.5 inches. Pop the heatproof bowl with the chocolate in it on top and set aside to allow the chocolate to melt, stirring occasionally.
Spoon just over a teaspoonful of melted dark chocolate into the bottom of a silicone mould (or use petit fours cases) swirling gently so it covers the bottom.
Pop the whole tray into the freezer for a few minutes until the chocolate has hardened.
Repeat melting in a clean bowl with half the white chocolate. Stir 1/4 teaspoon peppermint extract into the melted white chocolate and spoon the mixture over the top of the dark chocolate.
Repeat again with the rest of the dark, and then the rest of the white chocolate.
Coarsely chop or crush the candy cane with a rolling pin and sprinkle over the top of the still melted white chocolate after you've spooned on the final layer.
Refrigerate until set.
This would make a nice gift idea - place six chocolates into a small bag and tie with coloured ribbon and a gift tag!