If using a ganache on my cake, do I have to pour it over a cake that is already covered in BC? Or can I just use ganache as my frosting?
If I tell you what I have in mind to make, maybe you can suggest what I should do....
I'm going to make the "Darn Good Chocolate Cake" from this website in a 10" springform pan (3" deep). I plan on torting it to make four layers and alternate using rasperry filling and a ganache filling. Then I wanted to cover it in chocolate ganache.
Couple questions...
1) How many cake mixes will I need to make a full cake using the 10" springform pan (3" deep)?
2) Is the ganache that I will use as a filling be a different recipe than the one I'll use to cover the cake?
Thank you so much for all of your help!
Lisa
WOW.........that sounds so good. Can you send a piece to me? 
Not sure about your questions. I did a cake covered in BC and then drizzled ganache down the sides. It didn't completely cover it. You can see my cakes in my gallery.
And not for certain but I'd say two mixes or 1 1/2 mixes. I usually fill my 12x2 with 2 mixes, if that helps.
I havne't used that recipe, so hopefully someone with experience with it will chime in. I would think you'd need 1 1/2 times the recipe.
As to the ganache, you can pour the ganache over the entire cake as a topping, without buttercream under it. However, it will have to be thinner than what you would use a a filling. As a filling, you'll need to let the ganache set up some. Ganache can also be whipped to use as a frosting.
HTH
I would suggest that you use whipped ganache for the filling. It will have a better consistency. As it was already said you can easily pour the ganache right over the cake with or without buttercream on it. I made a cake a lot like that for my mother's birthday. It was a chocolate cake with chocolate mousse and raspberry puree for the filling and ganache for the "frosting". I took some of the ganache and let it set up a little and did a sort of crumb coat with it and then warmed up the ganache so it was thin and easily poured but not hot and poured it over the cake. 
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