Okay I am not to sure what you call this type of cake but I called it a tear apart cupcake cake, and this was my first one and it was pretty easy with some guided online tutorials. :) (Thank goodness for online tutorials!!!)
This is how i did mine. For this cake I used 19 cupcakes and tightly positioned them on my board with some buttercream on the bottom of the cupcake so that they don't move around. I filled in any holes where the cupcakes came together with buttercream. I then covered the tops of them with an even layer of pink buttercream (the evening out did take some time). After the buttercream was dry to the touch I traced the hello kitty face with a toothpick then outlined it with black buttercream. Then after outlining I filled it in with more colored buttercream. I used fondant for the whiskers. And tada my hello kitty tear apart cupcake cake. :)
I am definitely going to do more of these.