1 Mason jars you'll need two quart jars or one half gallon jar
Ingredients
1lb(roughly 15-22) young unripe black walnuts or butternuts soft enough that they can be cut through with a knife
2lb Brown sugar or Turbinado sugar
Instructions
Harvest and Prep the Nuts
Harvest unripe black walnuts directly from the tree. Younger is best, smaller than a ping pong ball. Older, more round nuts may be more tannic.
While it may be tempting to harvest walnuts that have already fallen, you will want to cut some of them in half to make sure they're pearly white and clean on the inside, without any spotting or deterioration. Wash the walnuts and reserve.
Wearing gloves, cut the walnuts in half using a heavy knife on a cutting board that won't stain. Older recipes often mention crushing or pounding the unripe nuts, which you could also do, but beware of splattering juice.
Mix the walnut with the sugar, then pack into a container that can accomodate the entire mixture. For the amount listed, you would want a half gallon mason jar.
Maceration
Allow the walnut-sugar mixture to sit at room temperature or outside for at least 30 days, and up to a few months, opening the jar occasionally to release carbon dioxide as the mixture will ferment. Shake or stir it occasionally to coat the nuts in the fermenting syrup and help prevent mold.
Boiling, straining and storing
After at least 30 days, scrape the sugary walnut mixture into a non-reactive sauce pot with high sides. On high heat, bring the mixture to a simmer to melt the syrup, turn the heat off and remove the walnuts using a slotted spoon and discard.
Finishing and Jarring
Bring the syrup back to a brisk simmer, turn off the heat and wait a minute for the foam to settle, skim off the foam. Pour the piping hot syrup into the jars leaving ½ inch of headspace, screw on the lids tightly.
The cooking process should take about 10 minutes. You're only melting the syrup and getting it hot, not reducing it.
Process the jars in a water bath, 10 minutes per pint. Some people simply turn the jars upside down and allow to cool and seal. The syrup will last for years and doesn't need to be refrigerated until it's opened. It can be a little tannic at first but mellows as it ages.
Notes
Aging the syrup
While this doesn't have as strong of tannins as nocino, there will be some. If you open the jars in the winter the tannins will have completely aged out and the syrup will taste like a light molasses.
Using the syrup
Use the finished syrup anywhere you would maple syrup, or in baking and drinks.