Preheat oven to 350° F. Spread the walnuts on a cookie sheet and toast them in oven for about 15 minutes, or until they're deep brown and fragrant. Remove the sheet from the oven and let the walnuts cool completely.

In a medium saucepan, toast the cinnamon pieces over medium heat. When the cinnamon has darkened slightly and is very fragrant carefully add the warm water, toasted walnuts, and then all remaining ingredients. Bring this mixture to a simmer. Adjust heat to low, cover, and cook for 20 minutes. Remove the mixture from the heat and allow to cool to room temperature (this can take around 2 hours). Transfer the mixture to a food processor or a blender, and pulse it once or twice, just to break things up a bit (you still want some larger pieces of cinnamon and walnut, so don't go too crazy here). Pour the mixture into an airtight container, cover, and transfer to the refrigerator for 8 to 24 hours to allow flavors to infuse.

Strain the mixture using a mesh strainer, discarding solids. Transfer to a glass bottle or other non-reactive airtight container. Reserve in the refrigerator.