Place graham crackers in a zip-top bag and crush with a rolling pin until finely ground. Mix in melted butter until the mixture resembles damp sand.
Press the crumb mixture evenly into a 9-inch pie dish, using the back of a spoon or your fingers to compact it. Bake in a preheated 350°F (175°C) oven for about 8-10 minutes until fragrant and slightly golden.
While the crust bakes, whisk together the egg yolks and sweetened condensed milk in a bowl until smooth and slightly thickened, about 2 minutes. The mixture should turn a pale, glossy yellow.
Stir in the freshly squeezed lime juice and lime zest until fully incorporated. The filling will thicken and become smooth with a vibrant green hue.
Pour the filling into the pre-baked crust, smoothing the top with a spatula for an even surface.
Bake the pie in the 350°F oven for 10-12 minutes until the edges are just set and the center still jiggles slightly when gently nudged.
Remove the pie from the oven and let it cool completely on a wire rack, then refrigerate for at least 2 hours or until thoroughly chilled and set.
If desired, top with whipped cream or meringue before serving for an extra touch of sweetness and texture.
Slice the chilled pie with a sharp knife, revealing the creamy filling nestled in the crisp crust, ready to enjoy.
