Whisk egg yolks, amaretto, and sugar in medium metal bowl to blend. Set bowl over saucepan of simmering water. Whisk mixture constantly and vigorously until thickened and instant-read thermometer inserted into mixture registers 140°F for 3 minutes, about 5 minutes total. Remove mixture from over water. Add cream and whisk until incorporated. Serve warm or chilled. (If serving chilled, zabaglione can be prepared 1 day ahead and refrigerated. Rewhisk before serving.)