Hello, if I use ganache instead of a crusting buttercream on my cake will it be fine in the heat. Or would you recommend crusting buttercream instead. I recently used buttercream on a cake and it began to slouch and melt due to the buttercream. Also if I'm covering a cake with white fondant is it best to use white ganache vs chocolate ganache ?

Thank you 

This video by Ann Reardon is interesting to watch.  She does a taste test of seven different kinds of frosting, but at the end of the video (at the 10 minute mark) she shows how each type of frosting holds up to heat.  Ganache melts the quickest.  Ermine, American Buttercream, cream cheese, and Italian meringue are the least heat sensitive. 

@ellimak13 ‍, how long was your cake setting at room temp, was it indoors or outdoors?  Because I had always heard that a fondant covered cake could not be refrigerated, I was leaving my cakes in their box on the kitchen counter after covering with fondant, for up 12 hours.  No matter how stiff I made my buttercream or whether or not I used all shortening instead of butter, the frosten would inevitably start to sag causing the fondant to droop and bulge.  I was advised by several professional friends that fondant cake can be refrigerated.  Now I refrigerate and it has solved the sagging problem.