Adjust oven rack to middle position and preheat the oven to 160°C. Crumb the biscuits in a food processor or in a plastic bag with a rolling pin. Toss with the melted butter. Spray a 22 cm x 4 cm deep pie dish with a non-stick cooking spray. Shake the crumbs level in the dish and then work some up the sides of the dish with the back of a tablespoon. Finally level the remaining crumbs on the base with the back of a tablespoon. Wipe the edge of the dish to remove loose crumbs.
Decant the lemon curd out of the bag into a medium size mixing bowl. Separate the eggs. The whites go into another spotlessly clean, medium size glass (not plastic!) mixing bowl. The yolks get added to the lemon curd. Mix the yolks into the lemon curd with a wire whisk. Decant the lemon curd mixture into the crumb lined pie dish.
Beat the egg whites with the electric beater on high speed. Beat until the whites stand up in soft peaks. Do not add castor sugar until this stage. Now add the castor sugar mixture (in the small foil pack) little by little while beating on high speed. You will end up with a snow white, thick and shiny meringue. Use two tablespoons to scoop and blob the meringue all over the curd filling. Start in the middle, no need to take it right up to the edges.Bake for 30 minutes. Then switch off the oven. Don’t open the door but leave the pie standing in the warm oven for 30 - 45 minutes to firm and dry out the meringue.Remove from the oven and leave to cool down. Store in the fridge for a good few hours to allow the curd to set before cutting. Stored in the fridge in an airtight container, it will keep for 3 - 4 days.
Take special care when separating the eggs. Even one speck of yolk in the egg whites will prevent the whites from beating to their full volume.Beat the whites until very fine bubbles from. The mixture must also stand up in soft peaks when the beaters are lifted. Only then can the castor sugar slowly be beaten in little by little. Once the meringue is made it should be shaped and baked as soon as possible or it will lose volume on standing.