In a large food processor fitted with an "S" blade, grind the walnuts into a fine meal.
Add in the rest of the ingredients, and process again until a sticky, uniform dough is formed.
Scoop the batter by heaping tablespoons onto a plate or baking sheet lined with parchment paper, to prevent sticking. Roll the balls between your hands, and roll them in cocoa powder, if desired.
Store the balls in an airtight container in the fridge for up to 2 weeks, or in the freezer for up to 3 months.
Nutrition information is for 1 of 12 balls. This will vary if you get more balls out of the recipe.If you don't have walnuts on hand, pecans would be the most similar substitute because of their texture. Almonds and cashews will be harder, so make sure to grind them well before adding in the rest of the ingredients.