I baked a 10" cake. Didn't change anything I've done in the past. It was cracking on top in the oven and was taking forever to cook. Almost an hour. I flipped it out after it cooled for 10 minutes and completely cracked and fell apart into 3 big pieces. UuuggHH! What causes this to happen? What can I do to prevent this? I used doctored BC cake mix. I had about 6 cups of batter. Thanks for the help.

And you are absolutely sure something wasn't accidentally left out? Just checking - I know you said you didn't change anything, but I know I have done it in the past Other than that I'm not sure - there are a lot of experts on here that I'm sure can help!