In small microwavable bowl, microwave chocolate chips and peanut butter chips uncovered on High 1 minute to 1 minute 30 seconds, stirring every 30 seconds, until melted and stirred smooth. Dip each cookie halfway into melted chocolate mixture, letting excess drip off. Immediately dip same half into chopped nuts. Place on waxed paper until set, about 1 hour. Store between sheets of waxed paper in tightly covered container.