My brother is turning sixteen on July 8th, and I am making his cake. I am planning on doing a little race track with cars on it. Just really simple. Buuut, I am making chocolate BC. How much would I need to to cover a thirteen by nine inch cake including the crumb coat? And how do I make a batch of chocolate BC, and still have about half of the icing batch white to color and decorate with?? And it's supposed to be a sort of rainy day, but I expect it to be in the 100's or 90's still with humidity... What recipe of BC should i use, one with all shortening? Wouldn't it make it taste bad? I'm kinda scared about smoothing this BC with copy paper, so some reassurance please! Thank you, fellow CCers!
make 2 batches of IndyDebi's recipe
http://cakecentral.com/recipes/6992/indydebis-crisco-based-buttercream-icing
it crusts really well and holds up in heat really well too.
to one batch add 8oz dark chocolate (I prefer Ghiradelli) and a "some" extra milk (add 1 tsp at a time to get right consistency. For even darker I've added additional cocoa powder (add to butter and blend in first) and even instead of extra milk, chocolate syrup (can there ever be too much chocolate -- NO!)
make 2 batches of IndyDebi's recipe
http://cakecentral.com/recipes/6992/indydebis-crisco-based-buttercream-icing
it crusts really well and holds up in heat really well too.
to one batch add 8oz dark chocolate (I prefer Ghiradelli) and a "some" extra milk (add 1 tsp at a time to get right consistency. For even darker I've added additional cocoa powder (add to butter and blend in first) and even instead of extra milk, chocolate syrup (can there ever be too much chocolate -- NO!)
Totally agree with Doug that if you want even "more chocolate" add some chocolate syrup...I make chocolate bc with the unsweetened chocolate as well but when I'm on a "death by chocolate" quest I will sub some of the milk for chocolate syrup... 
then...
just add cocoa powder -- and blend it in to the butter first.
---
FYI: although you start with melted dark chocolate, the result will be more like a milk chocolate once you work in all the powdered sugar --- which is why often add more powder and syrup to get it very Dark.
it will never be as "unsweet" as dark chocolate bar again due to all the sugar in icing.
thanks doug you always hav such useful information
It'll taste like chocolate with just cocoa. I use it all the time. 
Sorry to interrupt. I just wanted to offer up an alternative to chocolate BC, which I assume you'll be using for the ractrack. I made this cake (below) for my son's little friend and instead of Chocolate BC, I used regular White BC, then used a chocolate fudge cookie, baked in the same pan as the cake, so they were equal in size, and laid it on top. It went over REALLY well. It looked realistic and tasted so yummy. Anyway, it was so easy (cookie dough in a tube) I just wanted to share. Loads of luck with your cake!
Sorry to interrupt. I just wanted to offer up an alternative to chocolate BC, which I assume you'll be using for the ractrack. I made this cake (below) for my son's little friend and instead of Chocolate BC, I used regular White BC, then used a chocolate fudge cookie, baked in the same pan as the cake, so they were equal in size, and laid it on top. It went over REALLY well. It looked realistic and tasted so yummy. Anyway, it was so easy (cookie dough in a tube) I just wanted to share. Loads of luck with your cake!
Love the idea, but I'm not good enough to make that cake. I wish I was.
It'll taste like chocolate with just cocoa. I use it all the time.
as pointed out --
@Doug: If I just use Cocoa, will it not taste like chocolate??
YES -- but not DEATH by Chocolate!!! the only kind for me!!! 
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