1Heat oven to 350°F. Spray bottom and sides of 13x9-inch pan with cooking spray. In large bowl, stir cookie mix, butter and egg until soft dough forms. Stir in candies. Press dough in bottom of pan. Bake 18 to 20 minutes or until light golden brown.
2Meanwhile, in 2-quart saucepan, heat caramels and milk over medium heat, stirring constantly, until caramels are melted. Stir in peanut butter. Heat to boiling. Cook 2 minutes, stirring frequently. Remove from heat; stir in 1/2 cup peanuts. Spread over warm cookie base. Cool completely, about 2 hours.
3Spread frosting evenly over filling. Sprinkle with chopped peanuts. Refrigerate about 2 hours or until chilled. For bars, cut 9 rows by 4 rows. Store covered in refrigerator.