A quick before and after on mini cakes' how to's...
First you need a cake! LOL. Here we used a 10" marble cake baked for us by Whisk KL. Look how pretty the swirly patterns are :)
Use a round cutter to cut the cake to small round pieces. You could choose to work with these or...

...You could stack them up a layer to create tall minicakes...

Coat them with buttercream icing or ganache before covering them with fondant...
And tadaa...!
Oops, maybe not much of a "how to", but we forgot to take pics throughout the actual process. Ok, maybe next time ;)