Combine espresso and liqueur in a shallow dish. Dip sponge fingers, 1 at a time, into coffee mixture. Place, in a single layer, over base of a 2-litre capacity serving bowl.
Step 2
Fold cream through custard until just combined. Spread half the custard mixture over sponge fingers. Top with half the raspberries and half the chocolate.
Step 3
Repeat biscuit and custard layers. Cover and refrigerate for at least 2 hours or overnight, if time permits. Place remaining raspberries and chocolate in separate containers. Cover and refrigerate.
Step 4
Top trifle with remaining raspberries and grated chocolate just before serving.