Preheat the Oven: Begin by preheating your oven to 350°F (175°C).
Mix Filling: In a mixing bowl, whisk together the key lime juice, sour cream, grated lime zest, egg yolks, and sweetened condensed milk until the mixture is smooth.
Pour into Crust: Pour this tangy filling into your ready-made graham cracker crust, smoothing it out with a spatula.
Bake: Place the pie in the preheated oven and bake for about 10 minutes. This helps to set the filling beautifully.
Cool Down: After baking, set the pie aside to cool at room temperature before transferring it to the fridge.
Chill: Refrigerate the pie for at least three hours to let the flavors meld together.
Serve: When it’s time to dig in, slice yourself a generous piece, garnish with whipped cream if desired, and enjoy!