Neglected Food Bubbles: The Espresso Coffee Foam
You can actually simulate this at home with just a moka pot; no need for a fancy ultra-expensive espresso machine. Pour just a tiny amount of the espresso into a cup with sugar and beat it really hard with a spoon. Then pour the rest of the coffee into the same container. Voila, crema, or at least something that looks and feels like crema. I think this is a Cuban-American (maybe originally Cuban) innovation and growing up it was always referred to as "espumitas" (translated: little bubbles). The caveat is that you have to like your coffee sweetened for it to be useful. (Cubans always drink espresso sweet.)