Inside a bowl, mix together the Graham Cracker Crumbs (1 cup), Butter (1/2 cup) and Caster Sugar (1/4 cup). Then place and the mixture inside a pie tin lined with a plastic paper, pop it in the fridge until you are ready to use it.
In a separate bowl, mix together the Cream Cheese (8 ounce), and Sweetened Condensed Milk (14 ounce). Then add in the Lime Juice (2/3 cup), Vanilla Extract (1 teaspoon), and Lime (1), and mix everything well.
Evenly spread the filling over the crust, and place it into the fridge for about 4 hours. You can decorate with Whipped Cream (to taste) before serving. Enjoy!