Butterflying patties makes it dry, so browning it just enough to retain the juices is key.

As you can see from the photo, the patties are then wrapped around by an egg. It also has a slice of cheese and some sauce, you got to try it, I can't explain it. :-)
If you want the egg ones, you must say "special".
They are not sold in shops, but usually at nite markets (Pasar Malam) or in bazaars like this one.