No real wood is contained in chocolate bark (kidding)! However it is very decadent and scrumptious nonetheless. Chocolate bark is simply chocolate with any kind of nuts, candy, fruit etc, embedded within. This is done by melting chocolate, spreading it out, adding the “toppings” then allowing the mixture to solidify. The sheet of chocolate is then cut or broken into pieces. A popular type is peppermint bark.
Image used under Creative Commons from LittleMissCupcakeParis. CC BY-SA 2.0

Melted chocolate can be the sweet and beautiful finishing touches on about almost any desserts. However, if melted improperly, the chocolate can seize up or even burn. The best method for melting chocolate is using the double boiler technique as demonstrated in this video.
Photo Credit cursedthing. CC BY-SA 2.0