Grandmother's Graham Cracker Torte

My grandmother used to make this for me. I am reproducing it here with a few alterations.

Crust:
12 full sheets graham crackers (24 squares)
1/3 c butter, melted

Custard:
4 egg yolks
3 c milk
1/2 c + 2 Tbsp sugar
1/4 c cornstarch
1 tsp vanilla extract

Meringue:
4 egg whites
1/3 c sugar
1/4 tsp cream of tartar
1/2 tsp vanilla extract
1 Tbsp sugar
1 Tbsp cornstarch
1/3 c water

Place graham crackers in a gallon-size zip-top bag. Crush with a rolling pin. Remove to a medium bowl. Add butter; combine thoroughly. Reserve 1/2 cup of crumb mixture; press remaining mixture into the bottom of a 9"x9" square glass dish. Set aside.

Preheat oven to 325. For custard, combine egg yolks, sugar and cornstarch; whisk well.

Heat milk in a saucepan over medium heat. When milk boils, ladle a bit into egg yolk mixture. Whisk to combine and lighten yolk mixture, then whisk this mixture back into pot. Whisk continuously until mixture thickens, then pour onto prepared crust. Set aside.

In a medium bowl, whip egg whites until frothy. Add cream of tartar, 1/3 c sugar and vanilla. Whip until stiff peaks form. Set aside briefly.

In a small saucepan, combine 1 Tbsp each sugar and cornstarch. Pour in water; whisk to mix. Boil mixture for 15 seconds or until clear and thickened, then remove from heat. (This mixture will stabilize the meringue and give it additional texture.) Whip into egg whites by tablespoonfuls. When thoroughly incorporated, whip 10 additional seconds. Spread meringue over hot custard filling, sealing to edges. Sprinkle with reserved crumbs. Bake 20 minutes or until puffy and lightly browned.

Cool thoroughly before cutting. Refrigerate leftovers. Serves 10.