Semifreddo Allo Zabaglione

In a large bowl, beat the egg yolks with the sugar until very thick and lemon colored. Turn the mixer down to low and add the Marsala a tablespoon at a time. Pour mixture into a  saucepan over a very low heat or in a bain-marie and continue beating with a wire whisk until the mixture becomes foamy. Pour it in a bowl and let cool. Fold in the whipped cream and pour the mixture into a deep cake pan or baking dish lined with ladyfingers moistened with Marsala. Freeze for-at least 5 hours. Unmold onto a plate and garnish as desired.