I emailed her and here is what she said:
Well, there really isn't a recipe since you can bake almost any cake that you would like to make into this cake. What we used to bake the cake was a Wilton ball pan that you can pick up at Michaels or another craft store. Then just fill and frost with your favorite smooth frosting. After the cake is frosted, roll out some fondant (also available at Michaels in white that you can color or sold in cake supply shops in premixed colors or online) and drape the cake. Then decorate with fondant details to look like the Chickenpox cake. I hope this is what you need!
AJ's Moonlight Bakery