Soak all 12 pitted dates in very warm water for at least 10 minutes to soften.
In food processor or large bowl (if using immersion blender), combine the mashed sweet potato, coconut oil, 8 of the softened dates, and vanilla extract. Blend until smooth. Add egg, flours, salt, baking soda and spices and combine until a soft dough forms (it may be sticky). If using a food processor, scoop dough into a mixing bowl. Fold in chopped walnuts, additional 4 chopped dates and hemp seeds (optional).
Place bowl with dough in refrigerator, covered, and chill for at least 20 minutes.
Once dough has chilled, preheat oven to 350° and begin to scoop tablespoon-size balls of dough, evenly spaced, on parchment-lined baking sheet. Flatten each ball so that it is roughly 1⁄4 inch thick.
Bake for 11-12 minutes.
Serve warm or store in the refrigerator. May also freeze to enjoy later.