Zabaglione Ice-Cream Cake

Ingredients
6 egg yolks
1/4 cup marsala wine
3/4 cup caster sugar
3 cups cream
1 tsp vanilla extract
1/2 cup icing sugar, sifted
4 cups crumbled amaretto biscuits
10 oz raspberries
10 oz strawberries
1 tbs lemon juice

Directions:
Line base and sides of a 9 inch spring-form pan with non-stick baking paper and brush sides with melted butter.
Place egg yolks, marsala and 1/4 cup caster sugar in a bowl over a saucepan of simmering water. Whisk until doubled in volume then chill over a bowl of ice. Beat cream until it forms stiff peaks, then beat in vanilla and icing sugar and fold into zabaglione mixture.
Pour a quarter of the zabaglione mixture into the pan and freeze for 15 minutes. Top with a layer of amaretto biscuits then a layer of zabaglione. Freeze and repeat, finishing with a layer of zabaglione. Freeze for 4 hours.
Place remaining caster sugar in a saucepan with 1/2 cup water and bring to the boil, stirring. Reduce heat to medium and simmer for 5 minutes. Set aside to cool slightly. Add raspberries. Place in a blender and whiz until a smooth puree. Strain and discard seeds then add strawberries and lemon juice.
Pour the sauce over ice-cream cake and serve immediately.