This is the icing recipe I use in my bakery for cupcakes and for filling Macarons
1pkg powdered whipped topping mix
½ c. cold milk (International Delight French Vanilla coffee creamer works the best)
2 to 2 and 1/2 cups shortening (hi ratio) add the 1/2 cup more if you like it creamier
vanilla, almond or any other flavorings (I add to taste, not sure of exact amounts)
¼ c. light corn syrup
2lbs bag of powdered sugar
Dissolve powdered whipped topping mix with milk in small bowl – it will get thick, and not completely dissolve. Cream shortening and flavorings for about 5-7 minutes on medium speed, until it is fluffy and combined. Add alternately sugar and whipped topping/milk mix on low until combined. Add more milk if necessary. Add corn syrup and beat on high for 10 minutes until light and fluffy.
This does crust slightly. It makes about 4-6 cups of frosting. This must be refrigerated. I’m not sure how it would stand up in hot, humid climates, as where I am from is quite dry. Can be used for icing cakes, HOWEVER, because it is whipped on high speed at the end, it tends to get air bubbles, so you may have to work to get it smooth on a cake. I have had success doing this if you crumb coat your cake and set it in the freezer for a few minutes, then re-coat cake, set in freezer again, then smooth with viva paper towel.