It's not really part of a culinary tradition, debatably a fusion product, and isn't a thing in Mexico to my knowledge, but in and around Hong Kong there is a type of bun sold in bakeries called a Mexico bun. Its origin is from Chinese Mexicans who were deported by Obregon and Calles, who made and sold a bun with a cookie crust to emulate the conchas of Mexico using local ingredients. The result somewhat resembles the more well-known pineapple bun, an item which itself possibly traces its roots to the melon pan of Japan, where it was created by an Armenian pastry chef.