Prepare the sponge cake or ladyfingers and let them cool.
Slice the sponge cake into even layers.
If using, drizzle the fruit juice or sherry over the layers.
Layer the sponge cake in a trifle dish.
Add a layer of mixed berries on top.
Pour a layer of vanilla custard over the berries.
Spread a layer of whipped cream over the custard.
Repeat the layers until all ingredients are used.
Finish with whipped cream on top and garnish with berries and mint.
Chill in the refrigerator for at least 2 hours before serving.