I just got asked to make a cake for about 15 people, so what size pan can I use?
Depends on the size of cake each person will be eating. I usually go with a 2X2 piece, which is a nice sized piece of cake. Here are some guides to cake sizes and servings for both round and square cakes.
round cake guide:
square cake guide:
here's a chart to help you figure servings: http://www.wilton.com/wedding/wedding-cakes/wedding-cake-data.cfm
Here's a step by step on how to cut a cake to achieve those servings: http://www.cateritsimple.com/id10.html
here's pics of the 1x2x4 pc of cake to show that it's a regular dessert size piece of cake ... not 'paper thin' like most people think when they hear the words 'one inch': http://www.cakecentral.com/modules.php?name=gallery&file=displayimage&pid=
here's a thread that explains the sizing of sheet cakes and it includes a link on how to determine servings for sheet/square cakes just by "doing the math": http://cakecentral.com/cake-decorating-ftopicp-6799919.html#6799919
Thank you so much!! You guys have been a lot of help!!