Place into a blender, add 120ml (~1/2 cup) of the fruit kvass then blend on high until the figs are pureed. This will be 10 – 20seconds.
Transfer the mix to a large jar leaving plenty of headspace. I would suggest leaving at least the top 1/3 free. This allows for expansion as the fig puree ferments.
Add the remaining fruit kvass on top to cover the puree, put the lid on the jar and sit it in a bowl to catch any that might spill out. Leave to ferment at room temperature for 1-2 days. Taste it after the first 12 – 18 hours if you're in a hot climate and see its expanded. If you like the taste - move on to the next step. If you’d like it a little more sour leave it another 12-24 hours.
Transfer the fermented fig puree into a blender, add in the honey and cinnamon, and blend until smooth (just a few seconds).
Put the fermented fig butter into a clean jar, wipe the rim and put the lid on. Store it in the fridge for up to 3months (or more!).
Notes
Note 1: Fruit kvass is water with added fruit that has been left on the bench to ferment for a few days so it becomes effervescent. A recent post on my Facebook page shows you exactly how to make it. Water kefir or whey can also be used in place of this. Though keep in mind that whey will mean it may not be suitable for those with lactose intolerance.