Prepare the graham cracker crust
1-Preheat the oven to 350°F: Preheat the oven to 350°F.
2-In a medium mixing bowl, add the: In a medium mixing bowl, add the graham cracker crumbs and melted butter. Use a fork to mix until well combined.
3-Pour the crumbs into a 9-inch tart: Pour the crumbs into a 9-inch tart pan. Use a flat bottomed measuring cup to press the crumbs into the pan.
4-Place the pan onto a large baking: Place the pan onto a large baking sheet, and transfer into the oven. Bake for 11 minutes. Remove from the oven and allow to cool a bit while you make the filling.

Make the key lime pie
5-Turn the oven down to 325°F: Turn the oven down to 325°F. Ensure your key lime juice is strained and free of any seeds.
6-In a medium mixing bowl, add the: In a medium mixing bowl, add the egg yolks, sweetened condensed milk, key lime juice, lime zest, sour cream, and salt. Whisk until very smooth.
7-Pour the mixture over the graham cracker: Pour the mixture over the graham cracker crust.
8-Place the pie into the oven to: Place the pie into the oven to bake for 20 minutes, or until the centre has a slight jiggle, but the outside seems set.
9-Remove from the oven and allow to: Remove from the oven and allow to cool on a wire rack for 2 hours, before transferring into the fridge to set overnight.