4 egg yolks, beaten
2 (14 ounce) can sweetened condensed milk
1 cup key lime juice
1 (9 inch) prepared graham cracker crust
Preheat oven to 375 degrees F (190 degrees C).
Combine the egg yolks, sweetened condensed milk and lime juice. Mix well. Pour into unbaked graham cracker shell.
Bake in preheated oven for 15 minutes. Allow to cool. Top with whipped topping.
Hint**If you can not find any key lime juice then just use equal parts lemon and lime juice (best if fresh).
Piece of cake. Or pie as it were.