Prepare and make your pie crust. You can use a pre-made graham cracker pie crust or a homemade one.
Preheat the oven to 350°F and prep your ingredients.
In a medium saucepan, combine 1 1/4 cups granulated sugar, 6 tbsp cornstarch, and 1/2 tsp salt.
Gradually add in 1/2 cup freshly squeezed lemon juice, 1/2 cup cold water, and 3 lightly beaten egg yolks. Give it a stir.
Add 2 tbsp cubed unsalted butter.
Add 1 1/2 cups boiling water to the saucepan and bring the mixture to a full boil for 4 minutes, stirring constantly or it will burn.
Reduce the heat and let it simmer for 5 minutes. This will help thicken the filling.
Add 2 tsp lemon zest and stir.
Pour the lemon pie filling into the prepared crust and bake at 350°F for 20 minutes.
Once the pie is done baking, it needs to be set to thicken more. You must leave it in the refrigerator for 6 hours or overnight.
Notes
This pie must be boiled, baked, and refrigerated to become thick.
If you want an intense lemon flavor, add more lemon zest to the recipe.
When cooking the filling, ensure you’re watching it and stirring so it doesn’t burn on the bottom. The filling should be thick but still able to pour into the prepared pie crust.
Let the pie cool completely in the refrigerator before serving. This will help the filling to set up and thicken. I recommend that you allow it to sit overnight if you can.
Make sure to use freshly squeezed lemon juice. This will give the pie the best flavor.