I torted and filled a WASC cake with buttercream for an order for tomorrow but just found out they need a smaller cake (original cake was 12 inches and they now want 10 inch). I would like to save this cake if possible but will it be ok to freeze even though it has buttercream in it? Please help!!!

You should be fine.

Thanks. Do you happen to know how long I will be able to freeze it for?

I would think about 2-3 weeks if it's well wrapped. Lots of plastic wrap and foil. And put a baking soda box in your freezer to trap odors. I've frozen stuff up to a month with no ill effects.

Properly wrapped it will last up to 6 months.
If it is already iced w/b'cream put it into the fzr as is for about 1 hr to harden up, then wrap in plastic wrap, then foil; then put into a cake box which you then place into a plastic bag

Thanks so much for all your help. That is amazing! I never thought you could freeze it that long. I will be sure to wrap, wrap, box and bag. Thanks again!

You've gotton great advice on freezing. But, frankly, I'd ive them the 12" cake rather than rebake a smaller one. There's expense to rebaking.