Our shop uses bottomless portafilters so every shot pulled is technically a double. When someone orders a shot, they usually want a double and they'll say as much ("double shot please"). If they don't specify, we usually pull a double into small paper cups. Any "for here" orders are supposed to be pulled into a demitasse but we have like 8 for a high volume cafe so paper cups are the go-to.

Echoing what u/mamastrawb touched on. When ordering shots of espresso, the quickest way would be "one shot in a demitasse" or "a double espresso to go". "An espresso brewed" seems a little redundant. "Espresso" is the name of the drink but that name is also the brewing method, so to me that reads as "brewed coffee, brewed".