Put the walnuts into a food processor and process until smooth, scraping down the sides occasionally.
Add the butter, cinnamon, and syrup to the food processor and continue to process until the mixture is uniform. Pour it into a bowl and chill for at least 2 hours.
Using a cookie scoop or gloved hands, roll into 10-14 evenly-sized balls, working quickly to avoid melting. Store the balls in the refrigerator.
Macros for one ball, counting 12 balls total in the recipe: 120 calories, 1 gram net carbs, 2 grams protein, 14 grams fat.