By Karla Cripps and Kocha Olarn, CNN Bangkok (CNN) — There are said to be more than 200 types of mangoes grown in Thailand. But when it comes to creating one of the country’s most beloved desserts, khao nieow mamuang, connoisseurs say few varieties will do. Better known to the rest of the world as mango sticky rice, it’s a deceptively simple dish. Slices of sweet, ripe mango are set next to a mound of glutinous rice that’s topped with a coconut-…