Italian Meringue Buttercream Frosting

Italian Meringue Buttercream Frosting
Yield about 4 cups
Prep time: 5 minutes  Total Time: 15 minutes

Ingredients:
5 large Egg Whites
3/4 cup Sugar
1/2 cups Corn Syrup
3/4 lb Softened Butter (3 Sticks)
1/2 cup Shortening
2-4 tablespoons flavoring (optional)

Method of Preparation:
1.  In a bowl beat the whites with an electric mixer until light and fluffy.   Meanwhile, combine the sugar and corn syrup in a small saucepan and heat, stirring constantly, until the sugar dissolves and the syrup comes to a rolling boil. ( The entire surface will be covered with large bubbles.) Immediately transfer the syrup to a greased 1-cup heatproof glass measure near the range.
2.  If using an electric hand-held mixer, beat the syrup into the whites in a steady stream.  Don't allow the syrup to fall on the beater or they will spin it onto the sides of the bowl.  If using a stand mixer, pour a small amount of syrup over the whites, with the mixer turned off. Immediately beat at high speed for 5 seconds. Stop the mixer and add a larger amount of syrup.
3.  Beat at high speed for 5 seconds.  Continue with the remaining syrup.  For the last addition, use a rubber scraper to remove the syrup clinging to the glass measure.  Continue beating until completely cool.
4.  Gradually beat in the butter and shortening and, if desired, any optional flavoring.  Place in airtight bowl.  Bring to room temperature before using. Rebeat to restore texture.