My first thought was Chocolate, because people often get chocolate bunnies and such at Easter, and perhaps your friend's Burmese will have those chocolate markings? But Mocha would be fine. If your friend named the kitten Chocolate, it could be shortened to "'Late" (pronounced "Lot,") or "Choc" or "Chocs" or "Chocky." I would probably not use that name myself - which is why it is funny that it popped into my head - but that is the first name I thought of, so I thought I would mention it.