Grandmas Lemon Meringue Pie

{Well, it's not actually my grandmas recipe...i found it online, somewhere...}

Here is the recipe:

Filling:
1 cup sugar
2 T flour
3 T cornstarch
1/4 t salt
1 1/2 cup water
2 lemons, juiced, zested
2 T butter
4 egg yolks beaten

1 9 in. pie crust baked
4 egg whites
6 T sugar

Preheat oven to 350

To make filling:
In a medium saucepan whisk together sugar, flour, cornstarch and salt. Stir in water, lemon juice and zest. Cook over medium high heat stirring frequently until mixture comes to a boil. Stir in butter. Place egg yolks in a small bowl and gradually mix in 1/2 cup of hot sugar mixture. Whisk eggs yolk mixture back into sugar mixture. Bring to a boil, stirring constantly until thick. Remove from heat and pour into baked pie shells.

To make Meringue:
In a large glass or metal bowl whip egg whites until foamy. Add sugar gradually. Whip until stiff peaks form. Spread over pie sealing edges @ crust. Bake for 10 minutes until meringue is golden brown.