Line a 13-in. x 9-in. pan with foil and butter the foil with 1 tablespoon butter; set aside. In a large heat-proof bowl, combine the candy bars, chocolate chips and marshmallow creme; set aside.
In a large heavy saucepan over medium-low heat, combine the milk, sugar and remaining butter. Bring to a boil, stirring constantly. Boil and stir for 4-½ minutes. Pour over chocolate mixture; stir until chocolate is melted and mixture is smooth and creamy. Stir in walnuts. Pour into prepared pan. Cover and refrigerate until firm.
Using foil, lift fudge out of pan; cut into 1-in. squares. Store in an airtight container in the refrigerator.
