This is the cake section that I teach at the Professional Culinary Institute in Campbell, CA.
We are on day two and learning both about cakes and mixing methods but also about the many uses of ganache. On day one we made a batch of ganache to let set up for icing our cakes. While the cake then rests in the refrigerator, we make a fresh batch of warm ganache to pour over the cold cake. It sets up quickly so while you must encourage it over the sides of the cake, you must not spatula it too much or it will get streaky and have drip marks. I use a one to one formula for the ganache, chocolate to heavy cream and have the best success with a chocolate that is less than a 60% cocoa content.
We then learned how to pipe out filigrees using coating chocolate and placed them on piping we made with the drippings of the ganache.