Line 9”x13” pan with foil and grease foil with 1 tablespoon butter. In large heat-proof bowl add candy bars, chocolate pieces, marshmallow creme, and walnuts.
In saucepan heat milk, sugar, and remaining butter over medium-low heat. Boil for 4 minutes stirring often.
Pour hot milk over chocolate and stir until well combined. Pour into foil-lined pan and level with back of spoon. Cover and refrigerate for 2 hours or until firm.
Lift fudge from pan using foil. Cut into 1” squares and keep in airtight container in refrigerator for up to 3 weeks.