Kit Kat's flagship boutique Chocolatory in Tokyo has unveiled a new Kit Kat bar that's filled with cake. SoraNews24 reports that the Gateau Mignon Kit Kt features rich chocolate cake and icing buried inside a traditional Kit Kat bar. The recipe took pastry chef Yasumasa Takagi over a year to develop because he wanted to perfect the texture and balance of sweetness. Unfortunately for chocolate fans, the Gateau Mignon is only available in Tokyo. However, if you find yourself in Japan, three bars will cost you roughly $13.