Preheat the oven: Start by preheating your oven to 350°F (175°C) so it's ready for the crust.
Mix the crust: In a bowl, combine the graham cracker crumbs and melted butter until the mixture resembles wet sand.
Press and bake: Firmly press the crust mixture into the bottom and up the sides of a 9-inch pie dish. Bake for 10 minutes, then let it cool slightly.
Whisk the filling: In a large mixing bowl, vigorously whisk the egg yolks, sweetened condensed milk, and key lime juice until fully combined and smooth.
Pour and bake: Pour the luscious filling into your pre-baked crust. Return to the oven and bake for 15 minutes, until the edges are set but the center still has a slight jiggle.
Chill completely: Let the pie cool to room temperature, then transfer it to the refrigerator to chill for at least 3 hours (preferably overnight) before slicing.