2In a large glass or metal bowl, beat egg whites until stiff peaks form. Set aside.
3In a medium bowl, beat egg yolks, then stir in condensed milk, lime rind, and lime juice. Mix well, then fold mixture into beaten egg whites. Pour mixture into graham cracker crust.
4Bake in preheated oven for 10 minutes. Chill before serving. Garnish with whipped topping if desired.