Detailed method

• Preheat the oven to 170°C (conventional). Lightly grease a shallow ovenproof dish of approximately 2 litres.
  
• Whisk the custard sugar, cake flour and salt together in a heatproof bowl. Heat the milk until steaming and almost simmering, but not boiling.
• Gradually whisk a little hot milk into the flour mixture to make a smooth paste. Add the remaining milk slowly, whisking well. Return the mixture to the saucepan.
• Cook over low heat, stirring continuously and scraping the base of the pan, until the custard thickens and the flour has cooked through, about 5–8 minutes. Remove from the heat.
• Lightly beat the egg yolks. Whisk a few spoonfuls of warm custard into them to temper, then stir back into the custard with the melted butter and vanilla. Do not boil after adding the yolks.
• Pour into the prepared dish and bake for 20–30 minutes, until the custard is just set and lightly coloured. Deeper dishes may need longer; the centre should have a gentle wobble.
• Warm the apricot jam briefly so it spreads easily, then gently dot or brush it over the hot custard.
• In a clean, dry bowl, whisk the egg whites until soft peaks form. Gradually add the caster sugar, beating until the meringue is thick, glossy and holds firm peaks.
• Spoon the meringue over the jam, spreading to the edges and making soft peaks. Increase the oven to 200°C and bake for approximately 5–8 minutes, watching closely, until golden. Serve warm.