Crumble the sponge fingers or cake into the bottom of 6 individual ovenproof dishes. Drizzle the orange juice over the tops, then add the mixed fruits. Dollop the custard over the tops.
Whisk the egg whites in a clean, dry bowl until stiff peaks form, then gradually whisk in the sugar, a spoonful at a time, until all the sugar has been added. Keep whisking for another 1–2 minutes until the mixture is thick and glossy.
Spoon the meringue mixture over the top of the custard in large swirls. Place the dishes on a baking sheet. Cook in a preheated oven, 160°C (325°F), Gas Mark 3, for 20 minutes until the meringue is golden brown on top. Serve warm.