Hello!

i was just wondering, for example if a standard two layers of cake sandwiched together serves say 15 ... if I was to do it as a double height for a tall cake would that then mean it serves 30? Is it as simple as just doubling the servings for tall cakes? 

Thanks!

If you are doing an 8" round two layer cake, then yes it would serve 15 (according to the Wilton chart, you should get 20 servings from an 8" round cake).  

If you did a 4 layer, 8" round cake with a cake board in the middle (so basically two cakes stacked on top of each other), then yup it is as easy as doubling the serving size.  

But if you don't separate the layers with a cake board then you will only have 15 servings of a very tall cake.