I just got an order for a stacked sheet cake --- a 9"x13" on top of a 11"x15". Typically I would prepare each cake seperately then assemble them when I delivered and set the cake up. In this case, the customer is picking the cake up, so it has to be assembled and ready to go. Would I just stack the 2 cakes together without anything (but icing) between and then dowel the whole way down? Would I even have to dowel? I want the customer to be able to easily serve the cake, what would you suggest? Thanks for your imput!

Are they single layers? If so, you don't need to put boards between. The customer can just cut larger pieces from the outside, then smaller pieces when she gets to the double layer. You also don't need dowels all the way through.

If the two cakes are two layers each, then you must definitely board and dowel between.

Yes they are single layers. I was thinking the same thing as you suggested, I just wasn't sure if that was the best way to go. Thanks for your help!!!