The froth on the top of an espresso is called “crema”.
Any brewing method that extracts the coffee under pressure pushes oils from the coffee beans and creates the foam on top of the glass. Both traditional Espresso machines and Nespresso machines push water through the coffee under pressure. That action is what produce the crema.
It is a hot topic in the world of high-end coffee as to whether it enhances flavor or detracts from it. But no doubt, it looks beautiful.
If you pour a Macchiato pod, you can do your own test. Pour a shot and let it settle. Remove it with a spoon and taste the crema, it is the perfect way to decide if it is something, you want in your shot.
There is also a misconception that crema is a sign of quality. That is not necessarily the case. Each origin and bean type produces different amounts of crema.
The most expensive coffee in the world (a Panama geisha) produces very little crema. Robusta on the other hand is a very cheap version of coffee. It’s a different plant, and produces massive amounts of cream but tastes very earthy (most of it isn’t that great in our opinion).
So crema is a lovely looking thing - but in itself it doesn’t mean your morning coffee shot is 'good' or 'bad'