Whisk Sugar and egg yolks to blend in large metal bowl. Set over pan of barely simmering water (do not allow bowl to touch water); whisk constantly until mixture thickens and thermometer registers 160 °F, about 6 minutes. Place bowl over large bowl filled with ice; continue whisking until zabaglione cools (Light foamy custard-like dessert served hot or chilled), about 3 minutes. Whisk mascarpone to loosen in another large bowl; in 3 additions, foldin zabaglione. Whip cream, vanilla, and cinnamon in small bowl until soft peaks form; fold into zabaglione. Makes 6 servings.