1.To make lemon curd, place ingredients in a small heatproof bowl over a small saucepan of simmering water; stir constantly, until mixture thickens slightly. Remove from heat. Cover surface of curd with plastic wrap; refrigerate until cold.
2.Preheat oven to 180°C. Line a 12-hole (80ml) muffin pan with paper cases.
3.Beat butter, rind, 2/3 cup sugar and eggs in a small bowl with an electric mixer until light and fluffy. Stir in coconut, then sifted flour and milk. Spoon mixture into cases; smooth surface.
4.Bake cakes 20 minutes or until a skewer inserted into the centre comes out clean. Cool on wire racks. Increase oven to 220°C.
5.Cut a 2cm deep hole in the centre of each cake, fill with lemon curd.
6.To make meringue, beat egg whites and 1 cup sugar in a small bowl with an electric mixer until thick and glossy.
7.Spoon meringue into a piping bag fitted with a 1cm plain tube. Pipe meringue on cakes and place on an oven tray. Bake 5 minutes or until meringue is browned lightly.