Chocolate must be tempered when you attempt to pipe it. The easiest way is to chop the chocolate you want to melt, take 3/4 of it and place in a microwave safe bowl. Microwave in 20 second increments, stirring in between, until chocolate is melted. Immediately dump in the remaining 1/4 of the chocolate and stir until it melts. Once melted, I just pour it into a plastic resealable bag fitted with a small, plain tip (1/8"-1/4" opening) and pipe the chocolate onto a sheet tray lined with parchment paper. It only took 20 minutes or so for my trees to set up. I didn't attach the trees until shortly before service, I didn't want the moisture of the cake to wilt the trees.
Here is a picture!
|Creamy Chocolate Cheesecake|