Pour the pear juice into the pan and bring to a rapid boil.
It's ok to walk away and do other things, but you'll want to set a timer to check on the syrup every 15 minutes.
Light spiced pear syrup
When about 2-1.5 cups remains, strain the syrup to remove and impurities, then pour into a mason jar with a tight fitting lid. Process in a water bath or store in the fridge for up toi 6 months.
Full-bodied pear molasses
Continue reducing the liquid until it's a dark color and you can see the pan through the syrup when a spoon is dragged through it. There should be exactly one cup remaining.
The syrup is extremely stable and can be stored on the counter like honey.
For long term storage, pour the syrup into a jar and process in a water bath canner for long term storage. 8 minutes for an 8oz jar.
Video
Notes
The light syrup will retain the aromas of the spices. In the full-bodied molasses they'll be more in the background.