In a clean, dry bowl whisk the egg whites until they reach firm peaks.
Gradually add in the castor sugar one tablespoon at a time, whisking between additions.
The mixture should be stiff and glossy. Don’t overbeat.
Spoon or pipe the meringue onto the filling.
Bake for 10 – 15 minutes or until the filling is set and the meringue is browning slightly.
Let the tart cool off completely and put in the fridge to set.