I make sugarshack frosting with 1/2 shortening and 1/2 butter. (Can't seem to get it really smooth w/just shortening) In the summer months I have just been doing shortening because I have heard horror stories on how frosting can slide down the sides of the cake with real butter. How much heat can the 1/2 butter frosting take?
I use a combination of SugarShack's and IndyDebi's recipes. I use SugarShack's ratio, but add the Dream Whip that Debi suggests.
I have always used a ratio of butter in the recipe - SugarShack uses 5 cups of shortening and 5 lbs of PS. I do 1 cup butter and 4 cups of shortening. I've never had an issue with the bc falling off the cake or melting.
Put butter on counter. Grab clock, time it when it melts.