Yes, I have used the "used" nuts to make a less potent beverage referred to as "Thrifty Italian" - just Google it for the recipe or ask me if you can''t find it.
On a related subject, I have made nocino, a traditional Italian after-dinner drink using the traditional Modenese recipe (and have also made vin de noix) for years, with immature nuts from a black walnut near my home. Unfortunately that tree is having a bad year this year. I discovered some butternut (Juglans cinerea, aka white walnut) trees in a park nearby and wanted to ask if anyone has ever made "butternut nocino" or if anyone knows if the flesh around the immature butternut is non-toxic like the black walnut is? I have found very few references that say that butternut is not poison (or is otherwise not a good idea to use) so I thought someone here might know for sure, either from research or from practice. Thanks in advance!