Place dates in a microwave-safe bowl; heat in microwave for 30 seconds.
Blend dates, cashews, walnuts, almonds, raisins, cinnamon, allspice, and nutmeg in a food processor until evenly mixed and easily holds together. Press mixture onto the prepared baking sheet; tightly cover with plastic wrap. Refrigerate mixture until solid, at least 30 minutes. Remove from refrigerator and cut into bars.