Line a 13x9-in. baking pan with foil, letting ends extend over sides by 1 in. Grease the foil with 1-1/2 teaspoons butter; set aside., In a large saucepan, combine chocolate chips, milk and the remaining butter. Cook and stir over medium heat until mixture is smooth. Remove from the heat; stir in 2 cups peanuts. Place marshmallows in a large bowl; add chocolate mixture and stir well. Spread into prepared pan. Sprinkle with additional peanuts and marshmallows. Refrigerate until firm., Using foil, lift fudge out of pan. Cut into 1-1/2-in. squares.