A friend asked me to make a pillow cake for her grandaugter's birthday. She needs it to serve about 15 people. I guess in general, what are the rules of estimating servings for a cake? She says that she typically cuts larger pieces (as opposed to wedding size servings).
I wondering if I should so a round cake on the bottom and put the pillow cake on top.
Its not an earthshaking problem, I just thought I would see if I could get some advice.

Thanks!

Andrea