Instructions

  1. In 2-quart saucepan, combine sugar, flour and cocoa.
  2. With wire whisk, gradually stir in milk until smooth.
  3. Cook over medium heat, stirring frequently, until mixture has thickened and boils.
  4. Reduce heat to low; cook 2 minutes, stirring constantly.
  5. Remove from heat; cool completely.
  6. In medium bowl, with mixer at medium speed, beat butter until creamy.
  7. Gradually beat in milk mixture, melted chocolate and vanilla.