Line 13x9x2 inch baking pan with foil. Sprinkle 1 cup of the peanut on bottom of pan; set aside. Combine sugar, evaporated milk, butter and salt in large saucepan over med. Heat, stirring occasionally. Bring to full rolling boil. Cook 4 to 5 min. Stirring constantly. Remove from heat. Add marshmallows and peanut butter chips; stir vigorously 1 min, until marshmallows melt and blend. Pour over peanuts in pan. Sprinkle remaining peanuts over fudge; press down lightly. Chill until firm (about 2 hours). Cut into diamond or rectangular shapes. Drizzle with melted chocolate, if desired. Makes about 2 lbs.