Whip egg whites with cream of tartar medium speed until foamy, then increase the speed to high and gradually pour in the granulated sugar and icing sugar and continue whipping just until the whites hold a medium peak when the beaters are lifted.
Remove the plastic wrap from the hot lemon filling, then GENTLY dollop meringue directly onto the filling
Be sure to spread the meringue so that it completely covers the lemon filling and connects with the outside crust.
Dollop the remaining meringue onto the pie and use the back of your spoon or spatula to lift up the meringue and creates the spikes.
Bake at 325F for about 20 minutes, until the meringue is nicely browned OR use a torch to brown the top.
Cool the meringue completely to room temperature before chilling for at least 4 hours.