In the bowl of an electric mixer fitted with a whisk attachment, add the sugar, Creme Bouquet, vanilla, salt, and hot water; mix on high speed for 8 to 10 minutes. Turn off and scrape the sides of the bowl occasionally.
Add the butter and shortening; continue to mix for 8 to 10 minutes until icing is glossy and shiny.
This is enough icing for a 3 layer 8" cake.
Icing will keep in the refrigerator for up to one month.
Bring to room temperature and whip again.