This is Rompope
Rompope is an alcoholic beverage which was created in Puebla at the Convento de Santa Clara. It is an eggnog-like drink made from, not surprisingly, eggs, milk, vanilla flavouring and aguardiente. Additional ingredients can be added to create different flavours such as strawberry, cinnamon or coffee. Weirdly, no matter what flavour it is, the colour always ends up fluorescent (as seen in the picture below). Like the subjects of many of my previous posts, Rompope is very poblano, and is sold across the city and state. You can buy it easily wherever you go; for example in Cholula (see post here) and cantinas like La Pasita (see post here).