LINE 8-inch square baking pan with foil, with ends of foil extending over sides of pan; set aside. Place sugar, butter and evaporated milk in large heavy saucepan.
BRING to full rolling boil on medium heat, stirring constantly. Boil 5 min., stirring constantly. Remove from heat.
ADD chocolate; stir until completely melted. Pour into prepared pan. Refrigerate 3 hours or until firm. Remove fudge from pan, using foil handles. Cut fudge into 24 pieces. Store in tightly covered container in refrigerator.