Ladies, Meet the Sugarpixy. She lives in the Cayman Islands. If anyone can deal with heat and humidity, I’d say it’s this girl! I found her recipe when she first posted this video and as the posters have stated above, sometimes you have to tweek a recipe to your climate. I live on the Outer Banks of North Carolina. Most of the time, the humidity is above 70%, some days 90% (with no rain!) and heat indexes over 90*. In the winter, I use a 50/50 ratio of butter/ shortening. During the summer, I use a 45/55 ration of butter to shortening. It makes a difference. Also: after watching this video, I started adding cornstarch and omitting meringue powder. It made a difference for me. Good luck!
http://cakesdecor.com/entries/169-how-to-get-smooth-butter-cream-that-stands-up-to-heat-and-humidity
Psalm 127:1 Unless the LORD builds the house, the builders labor in vain.
