it's included in the prusaslicer download zip file and will install if you tick the box to install it.

You've probably forgotten colin, as you were thinking about pizza at the time ;-)

useful bit of kit

if you have multimeter - just put it across the fan pins - no need to go anywhere near the big power lines.

There is also a jumper that dtermines whether it';s 12 or 24 v for fans and heaters and things.