Preheat oven to 180 °C (160 for fan oven) (350° F). Place 6 large or 12 small paper cases in a cupcake tin.
Cream the butter and sugar until light and fluffy and stir in the vanilla. Sift in the flour, salt and custard powder and lightly fold into the mixture alternately with the eggs until well blended.
Spoon into the paper cases and bake for 20 – 25 minutes until golden brown and springy to the touch.
When the cupcakes have completely cooled, cut out a hole the size of a 2p coin from the centre of each cake. Fill with lemon curd.
To make the meringue cuite
Sieve the icing sugar into a heat resistant bowl with the egg white.Place your bowl over a half-full pan of simmering – not boiling – water, whisk with an electric mixer until the mixture is thick and glossy, approximately 10 minutes.Place the meringue mixture into a piping bag and pipe on top of the cupcakes.
Increase the oven temperature to 230 °C or use the top grill function and bake the cupcakes with meringue topping for a further 5 minutes. You can also use a cooks blowtorch to brown the tops.