I am creating a 4 tier stacked cake for an anniversary party, but the woman who ordered the cake does not care for buttercream icing. The cake will be fondant covered, but will be sitting outside. Temperatures these days range from 70 to 85 degrees. Does anyone have a non-buttercream recipe that would be okay sitting outside for a few hours? I'm at a loss and would appreciate the help!

Ganache (either chocolate or white chocolate).

http://cakecentral.com/recipes/2116/chocolate-ganache-1

HTH