Line a 13x9-in. pan with foil; grease the foil with 2 teaspoons butter. , In a large heavy saucepan, combine the sugar, milk and remaining 1 cup butter. Bring to a rapid boil over medium heat, stirring constantly. Cook, without stirring, for 2 minutes. Remove from the heat., Stir in marshmallows until melted. Add all chocolate; stir until melted. Stir in vanilla. Immediately spread into prepared pan; cool for 1 hour., Score into 1-in. squares. Refrigerate, covered, until firm, about 3 hours. Using foil, lift out fudge. Remove foil; cut fudge. Store between layers of waxed paper in airtight containers. Decorate as desired.