I have some MMF that I made back in October that has been wrapped up and in a big plastic container in my cabinet. Can I use this now? I'm more concerned from an edible standpoint, will it make someone sick? Or is the issue that it will just be hard and need some help being softened up?
I also have a question about a 2 tier cake. The top tier will be 6" and the bottom will be 9". Do I need to place dowl rods in the center?
I don't think that 6" is going to put much weight on that bottom tier so I don't think you have to worry about it.. that being said.. I usually dowel any of my tiered cakes.. just for piece of mind!!! So while I don't think you have to, I do!!!
MMF.. I freeze and unfreeze all the time with that stuff.. anytime I need a little blue, a little whatever color.. I take it out of the freezer, let it come to room temp, use it and put it back in the freezer. I don't know why it would go bad with it being marshmallows and powdered sugar!
If the MMF was made with only marshmallow, sugar and crisco, the shelf life is almost indefinite as long as it is stored in a sealed container. Think of it as candy. May get "stale" eventually, but not really "bad". As far as the cake goes, yes, I would use dowels. It may not seem necessary, but even a 4" cake can apply enough weight to squash the one beneath it.