A gray Tuesday morning, the usual coffee in its stoneware mug, and suddenly a craving for something different. Not a long coffee, not a 6-euro latte. Just this recipe that the Vietnamese invented in the 40s, when milk was scarce and they had to improvise with what was at hand.

Look at this glass. Two distinct layers: below, a dark espresso, almost black, and above, a thick ivory foam, lightly golden like a flan freshly out of the oven. As you bring the glass to your lips, you first feel the full-bodied coffee, then the foam—warm, slightly sweet, with that scent of beaten egg that recalls raw sponge cake batter. The texture under the tongue is silky, dense without being heavy. Two flavors in a single sip.