Preheat the oven to 180°C (350°F) and lightly grease a shallow ovenproof dish with Unsalted Butter.
In a saucepan gently heat Whole Milk with the Vanilla Extract, the Lemon Zest and a little of the Caster Sugar until the sugar dissolves and the milk is steaming (do not let it boil); remove from the heat.
Put the White Breadcrumbs into a large bowl, pour the warm milk mixture over them and stir to combine; leave to soak for 5 minutes, then stir in the beaten Egg Yolks until smooth and homogenous.
Pour the mixture into the prepared dish, smooth the top, place the dish inside a larger roasting pan and pour in hot water to reach halfway up the sides (bain-marie). Bake for 30–40 minutes, or until the centre is just set.
Carefully remove the pudding from the water bath, discard the water and while the surface is still warm spread a thin, even layer of Raspberry Jam over the custard.
Whisk the Egg Whites to soft peaks, then gradually add the rest of the Caster Sugar while whisking until you have a glossy, stiff meringue. Spoon or pipe the meringue on top of the jam, sealing it to the edges.
Return the pudding to the oven under the grill (broiler) for 2–5 minutes until the meringue is nicely golden, or carefully brown the top with a blowtorch. Allow to cool slightly before serving so the layers settle.
