Bittersweet chocolate frosting

---------- Recipe via Meal-Master (tm) v8.05
  
       Title: Bittersweet Chocolate Frosting
  Categories: Cakes, Chocolate
       Yield: 1 servings
  
   1 1/2 c  Sugar
       6 lg Egg yolks; room temp
       1 tb Light corn syrup
   1 1/2 c  Whipping cream
       6    Unsweetened chocolate;
            -chopped
       3    Semi-sweet chocolate;
            -chopped
   1 1/2    Unsalted butter; sliced
            Room temp
     1/2 ts Vanilla
  
   Mix sugar, yolks, and corn syrup in small bowl. Simmer
   cream in heavy 3 qt saucepan. Add both chocolates. Stir
   over low heat until smooth. Remove from heat. Stir in
   butter, then sugar mixture. Cook over low heat until
   temperature is 165-170~(about 10 minutes). Stir constantly.
   DO NOT SCRAPE SIDES OF BOWL (or candy monster will bite)
   Add vanilla. Beat with mixer until cool. Let stand until
   spreadable, about 1 1/2hrs. Use On Heirloom Chocolate Cake.
  
 -----