Line bottom and sides of 9-inch pan with foil, leaving foil overhanging at 2 opposite sides of pan. In large bowl, mix peanut butter, butter, graham cracker crumbs and powdered sugar until well blended. Press in bottom of pan.
In medium microwavable bowl, microwave white chocolate uncovered on High 1 to 2 minutes, stirring every 30 seconds, until melted and chocolate can be stirred smooth. Pour melted white chocolate over peanut butter mixture and spread to edges. Sprinkle with peanuts. Refrigerate 1 hour or until chocolate is set. Use foil to lift out of pan. Cut into 6 rows by 6 rows.