Line a 13x9-in. pan with foil; grease foil with 1-1/2 teaspoons butter., In a heavy saucepan, combine sugar, milk and remaining 3/4 cup butter; bring to a rapid boil over medium heat, stirring constantly. Boil 4 minutes, stirring constantly. Remove from heat; stir in baking chips and marshmallow creme until melted. Stir in vanilla. Immediately spread into prepared pan. Refrigerate until firm, 1-2 hours. , Using foil, lift fudge out of pan. Remove foil; cut fudge into 1-in. squares. Store between layers of waxed paper in an airtight container.