On the serving chart listed here, what does it mean when it says serving for 1 layer & serving for 2 layers?
If your referring to the Wilton serving chart in the articles section it does mention what the layers are: I've just added it here for you just in case you overlooked it (very easy to do as the eyes just usually zoom onto the chart )
"The figures for 2-inch pans are based on a 2-layer or 4-inch depth cake. The figures for 3-inch pans are based on a 1-layer cake which has been torted and filled to reach a 3-inch depth."
So basically it is saying:
If you are baking a cake in a 2" pan and you stack 2 of those together that would be considered a 2-layer cake.
If you are using the 3" pan (or using a 2" pan with a collar ) then just torte and fill just the one cake and it is considered 1 layer.
HTH and have a great weekend!