I discovered this video almost a year ago, and immediately knew that it was what I wanted to do for Mikaela's 5th birthday cake:
Happy Housewife - Barbie Cake TutorialThis one also helped a lot:
Betty Crocker Princess Doll Cake TutorialWith that, I was ready to go. I baked the first section in a Pyrex bowl. It took over an HOUR...

The other two sections were just regular circle pans. This is the part where is looked a little scary to me because I knew if I sliced the domed parts of the circles, I would lose height and I felt for sure that the cake sections would fall apart or crumble, crumble, crumble...
I took a deep breath and started putting on my crumb coat and just slathered it on where there were big gaps...whew! I think I'm going to make it! :)
With the crumb coat done, I put it in the fridge to set a while and then added the barbie doll so I could add the 2nd coat of frosting. Barbie is covered in saran wrap for easy clean up...

Then I used a cake decorating tip to add the frosting for the the top of her dress...

I just thought it looked funny to see her in the fridge while the frosting was setting!

Mikaela helped me add the finishing touches...

Yay! It actually worked! :) Mikaela loved it!