The people here are known for this - and it shows. It's 2/3 a floofy layer of egg foam (the raw eggs are whipped with condensed milk for ages so it puffs up and stabilises into a sort of custard. Below is a shot of strong, chocolatey, rich, almost syrupy Vietnamese coffee. Yum. My only gripe is that it's quite sweet, and it's more dessert than coffee, but what a delicious, kiddy treat this is!