I am making a cake that is to be carved into a ribbon for a American Cancer Society fund raiser. I baked the 1/2 sheet cake last night and while taking it out of the pan, it cracked. It did not go all the way through, however it is right down the middle. I froze the cake last night and am planning on torting and craving it tomorrow morning. Since it will have buttercream in the middle I hope it will be stable enough that it will not crack in transport to the event. I plan on covering with buttercream and then fondant.

Any suggestions to make sure I don't show up to the event with a broken cake!!

If you use buttercream as a "glue", frost your cake and then cover it with fondant, you should not have any 'cracks' showing through. I have cracked a cake a time or two myself and was able to cover it without issue. Good luck to you.

It should be fine. Just do what you said and make sure the board under it is sturdy.

If you've got a Micheals or Hobby Lobby nearby, purchase one of their 20 by 30 by 1/2" foam core boards and make your board from that. Much stiffer and sturdier than the thin cake boards doubled or tripled up.