Hi Tara,
Just to be clear, you’re talking about boiled icing (sugar and water heated and added to whisked eggwhites) not italian meringue butter cream right?
i’ve used boiled icing under fondant in a pinch before (i had some left over boiled icing that i needed to use), and the cake turned out okay. I even left the cake in room temp for a couple of days, and didn’t see any buckling or rippling.
As for rosettes, i don’t see why not, though i haven’t personally tried it out before.
Lainie, www.facebook.com/harina.cakes
