I froze my cakes like have seen everyone do then i put smb on top. cooled it, then while still cold i tried to put fondant but the condensation from the smb coming to room temp was melting my fondant. my question is why do i see and hear people put their butter cream covered cake in the fridge to cool up then put fondant on it but never hear of this.

Is your kitchen very warm? As opposed to room temp? Alternately is your fridge extra cold? I have never had this problem.

Some do chill their cakes and others don't. I like to put fondant on a cooled cake, not frozen though. I ice my cake after its completely thawed. I haven't noticed any meltling, so I'm not sure what is going on. I use a 1/2 butter, 1/2 shortening based buttercream.