Minimum viable User Testing lab set up

My need is to set up a User Testing facility, which allows observers to watch the session. I do not want people to hover around the user, who then feels like a lab rat. My constraint is that I cannot use any cloud based software (e.g. Lookback). I am currently capturing screen only via Quicktime on Mac.

I've read the post about the ideal lab, but that's way beyond my budget and constraint.

Is there any way to set up a viewing room where observers are able to watch the session (being able to see both screen and user and listen to what the user and researcher are saying), with no cloud based software and no streaming, so Skype or similar would also be out of question.

I am conscious the solution will be sub-optimal, but we have a very strict policy which limits what I can do.

Thanks