Well... how much do you know about magic? From what I've seen... whenever you cut a piece off, it replaces itself shortly afterwards.

[She tilts her journal to demonstrate, and pulls off a piece with her fingers. Sure enough, the cake seems to reform good as new with the piece still in her fingers.]

And... as to the question of is it the best tasting cake?

[She eats the piece in her hands, and then shivers in delighted contentment.]

I think it is! It seems that... it's whatever flavor its eater desires it to be the most. Even if you don't necessarily have any thing in mind, it seems like it will supply something according to your personal tastes. I don't know if it works for anybody who eats it but... that's how it's been for me. I found it at the foot of my bed this morning, with a simple tag saying it was from Santa... so I guess it was for Christmas?

[I unfortunately don't know what Rihanna is X3]