I am making the giant cupcake cake and was wondering how long it can be left out at room temperature before needing to be tossed? I am going to be baking with a standard box mix and home made butter cream icing made using water, not milk.

Thanks in advance for your answers!

Have a great day!

Box/doctored box cakes made (frosted/filled) with American buttercreams are very shelf stable.... Should be fine for at least a week, if it lasts that long!

HTH

P.S. The little bit of milk used in most American b/c recipes doesn't affect it's shelf stability. (The powdered sugar which is "hygroscopic" controls the "water activity" in whatever liquid you're using.)

Everything you ever wanted to know about making, decorating and assembling stacked/tiered/layer cakes:

http://www.cakecentral.com/cake-decorating-ftopict-605188-.html