Preheat the oven to 425°F and spray a 10x15x1-inch jelly roll with cooking spray.
Roll out the pie crusts until they are about ⅛ of an inch thick. You should be able to lay them on the cookie sheet and they will reach a little over ½ way with extra laying over the edges. The middle of the crusts will overlap like a ven diagram. You will have what looks like a big oval.
Use your fingers to press the middle crusts together and then roll the edges together and crimp them together to form a little wall.
Use a fork to prick the pie crust every 2 inches so that the crust doesn’t shrink when baked.
Brush the 1 Tablespoon of melted butter all over the crust and then sprinkle the edges with 1 Tablespoon of granulated white sugar.
Bake the crust for 15 to 20 minutes until it is golden brown. Remove from the oven and reduce the temperature to 350°F.
While the crust is baking, separate the large eggs, placing the yolks in a medium-sized mixing bowl and the egg whites in a large, dry metal bowl.
Using a stand mixer with the whisk attachment, beat the egg whites and ½ teaspoon lemon juice together on medium speed until foamy, about 2 to 3 minutes.
Slowly add in the ½ cup granulated white sugar, beating on medium speed, until the sugar is incorporated. Continue to beat until the mixture is glossy and stiff peaks form, about 10 minutes.
While the eggs are beating, whisk together the 1½ cups granulated white sugar, cornstarch, flour, lemon zest, and sea salt in a medium-sized saucepan.
Add in the whole milk and lemon juice and whisk until combined.
Cook over medium to medium-high heat, stirring frequently, until the mixture comes to a boil.
Add in 3 Tablespoons of salted butter and whisk until the butter is melted and incorporated into the mixture.
Remove ½ cup of the lemon mixture and gradually whisk it into the egg yolks.
Once completely incorporated, begin to pour the yolk mixture back into the lemon mixture, a little at a time, whisking continuously.
Return the mixture to boiling, whisking continually, and heat until the mixture is thickened. This should only take a few minutes.
Pour the mixture into the middle of the baked crust and gently spread it out to the edges with an offset spatula.
Scoop the meringue on top of the hot lemon filling. Start by scooping spoonfuls onto the edges of the filling and then place the rest, by spoonfuls, all over the middle. Use a spoon to gently spread the meringue to the edges of the crust to seal the pie and then all over the rest of the top of the pie until it is completely covered.
Bake at 350°F for 11 to 13 minutes until the meringue is golden brown.
Remove from the oven and allow the pie to cool for an hour at room temperature (do not remove from the jelly roll pan).
Chill in the refrigerator for at least 2 hours before cutting and serving