I am looking for something that gives my frostings more holding power in this extreme heat. I have tried to substitute 1/4 cup of HR Shortening to my american buttercream frosting recipe but I feel it just gives me a greasy sweet frosting as opposed to that nice full bodied butter taste in my original recipe. I don't want to compromise on the flavor for a more heat resistance frosting. I was thinking meringue powder? Does anyone have any ideas or tips on what else I could use to stabilize the frosting?

I do all butter frostings. I refuse if it is to go outside in the heat. Now if someone wants to take it upon themselves to move from a cool room to an outdoor oven, then that is up to them...but I always tell them my cakes do NOT do well outdoors. That being said, outside heat can still be an issue even if it is in an air
conditioned room (why is that?).

So I deliver a very cold cake. The butter frosting is nice and hard upon delivery and the cake can come to room temp slowly...and since most event cakes sit out for several hours before cutting, it works out great.