I'm making my first topsy turvy! How do you determine the number of servings since some of the cake gets carved out to stack the next layer? They want a 3 tier topsy turvy but only need a small cake for a first birthday party with at most probably 30 guests. They will probably use the top layer for the smash cake.

I use the Wilton party chart for all of my cakes. For topsy turvy cakes, I look at the chart and cut the serving # in half and then try to find the sizes that come closest to what I need.

For 30 servings, one layer each of a 9+8+7= 30

http://www.wilton.com/cakes/making-cakes/baking-party-cake-2-inch-pans.cfm

HTH
Rae