AI am looking to do the effect seen on this cake minus the oil rig on top. The blog that I found the cake on says that the oil effect was done using chocolate ganache oil. Any idea what is meant by this? I know what ganache is (although I've never used it), but I'm not sure what ganache oil is. Thanks! http://mainmadecakes.wordpress.com/tag/oil-rig-cake/

It looks like they used freshly made ganache, and poured whilst still warm/hot.  I think the title should have read chocolate ganache for the 'oil'.  Rather than it being a special type of ganache.

You could also use a chocolate mirror glaze - I think patissiere Adriano Zumbo has a recipe for one - but ganache is by far very easy and only 2 ingredients.

Thanks, Magic. That is what I thought. Now my only question is... Buttercream or fondant? Would warm ganache ruin the surface of the buttercream? And how much ganache? I don't want to accidentally cover my entire cake.

we used a generous amount of oil in our chocolate ganache fountains -- flows better -- don't know how that figures into the pictures though because nothing is moving -- idk

Buttercream or fondant...you choose.  Both would be fine.  I have made a 'melted chocolate icecream' on a cake iced in cream cheese frosting and it worked brilliantly.

I guess whatever your cake icing - let the ganache cool down as much as possible but still runny.  Slowly pour over cake until you get the look you are after.  I recall deliberately pouring right on the edges in strategic places to create an even looking overflow / drip line.  You wont need to make much - maybe 100-200g of chocolate/50-100g of cream.

I think I may also have 'dropped' my cake from a small height (say 1 inch) onto the bench to help settle /smooth out the ganache - just like you would 'drop' your chocolate moulds to remove air bubbles or 'tap' your cake pops.

There is also a 'ganache' recipe that uses chocolate and butter (instead of cream) - I'm thinking it might make for a more shiny look?

Other people use 'Ice Magic' (not sure if you have that product in your country) but I have heard it takes ages to set when not used on icecream. 

K8 - ooh I've never thought to use ganache in my chocolate fountain - that sounds delicious!!!  I do have to add a horrible amount of oil to make it flow tho, especially with milk chocolate, and therefore it tastes rather sickly too quickly.  You now have me thinking that a ganache made with extra cream (ie a chocolate sauce) would be ideal for the fountain.

Alright, I tried taking fresh warm ganache using the "traditional method" explained on this page. http://www.foodnetwork.com/recipes/master-ganache-recipe.html.  I immediately poured it onto a chilled buttercream cake but I don't think it was hot enough or runny enough because it just blanketed the top of the cake and a bit of the sides. It didn't make nice oil-drops that run down the cake like in the picture in my original post. Should I add a bit of oil? Shortening? Butter?

Did you remember to pour onto the edge of the cake (in various places around the rim), so that it oozed down the sides in the 'right places' .  You could do this pouring delicately with a dessert size spoonful - rather than straight from the saucepan.  

I am not sure how big your cake is, therefore dont' know how much ganache you will need.

That 'master' recipe is almost 1:1 ratio of chocolate to cream - my ganache recipes all say 2 parts chocolate to 1 part cream (ie 250g chocolate to 125g cream).   Surely your recipe would make for a runnier ganache that would take longer to set.

Also - I didn't have my cake chilled - my frosting was at room temperature  Sounds like yours set immediately before it could run down the sides.

Yes! Thanks Magic Mouthfuls. I tried it again and this time I achieved more of the look I was going for. I changed up the ratio and used less chocolate. I let my cake come to room temperature. And I added a tablespoon of butter. Voila! Thanks!