Beat egg yolks and sugar in a snow kettle or in a metal bowl over a hot water bath with a whisk until thick and creamy. (Be careful, keep scraping the edges free, otherwise the egg yolk will get too hot) Gradually stir in the marsala, stirring constantly. Take it off the water bath just before the boiling point and let it cool down. Stir occasionally. Crumble the biscuits. Line a loaf pan with cling film, whip the cream until stiff and fold into the ice cream. Pour half of the mixture into the mold, smooth it out, sprinkle with the biscuit crumbs evenly and drizzle with orange liqueur. Pour the rest of the cream over it. Hit the shape on the work surface several times to allow the air bubbles to escape. Cover the mold with aluminum foil and place in the freezer for at least 12 hours. Just before serving, turn the semi-frozen food out onto a chilled platter and peel off the foil. Cut the cream into slices with a knife dipped in hot water.