1Heat oven to 350°F. Spray bottom and sides of 13x9-inch pan with cooking spray. In large bowl, stir all cookie base ingredients except peanuts until soft dough forms. Press dough in bottom of pan. Sprinkle evenly with 2 cups peanuts; press lightly into dough. Bake 12 to 15 minutes until light golden brown. Cool 30 minutes.
2In 3-quart saucepan, heat marshmallows and butter over medium-low heat, stirring frequently, until melted. Stir in peanut butter, milk and peanut butter chips until smooth.
3Immediately pour marshmallow mixture over cookie base; spread evenly. Sprinkle evenly with 2 cups peanuts; press gently into marshmallow mixture. Refrigerate about 1 hour or until firm. For bars, cut into 10 rows by 6 rows. Store covered in refrigerator.