1.Beat eggs and sugar in a medium bowl with an electric mixer until thick and creamy.
2.Beat mascarpone and cream in a large bowl with an electric mixer until thick. Fold egg mixture into mascarpone mixture.
3.Place coffee and the boiling water in a coffee plunger; stand 2 minutes before plunging. Strain coffee through fine sieve into a medium heatproof bowl; stir in liqueur.
4.Dip half the biscuits, one at a time, briefly in coffee mixture to soften. Line the base of a shallow 2-litre (8-cup) serving dish with softened biscuits.
5.Spread half the mascarpone mixture over biscuits then top with grated chocolate. Slice half the strawberries thickly; scatter over chocolate.
6.Dip remaining biscuits, one at a time, briefly in remaining coffee mixture to soften. Repeat layering process with biscuits and mascarpone mixture. Cover; refrigerate 3 hours or overnight.
7.Slice remaining strawberries thickly; combine with raspberries, pile on trifle. Serve topped with some more grated white chocolate.