I need to simply cover an 8" cake with white chocolate ganache. Most of the recipes/ratios I've seen are for larger batches of ganache. Can anyone suggest how many ounces of chocolate and cream I would need to ice the cake with? I am filling with buttercream so it just needs to be enough to cover the outside. I will most likely be using bar chocolate because I'm not big on using chips for ganache, but I have never made white chocolate ganache so I am open to any suggestions.