To make the pie it is exactly like the pudding only separate the eggs and use the whites for the meringue. It is important to note all the eggs Pa used were jumbo, and nothing else will do!

Grandmother supervises the construction of a Chocolate Pie. Looks like she might even be giving Pa a few pointers!
Pie Filling:
2 toasted pie shells
4 cups milk
4 jumbo egg yolks, beaten
1 cup sugar
6 tablespoons unsweetened cocoa
8 tablespoons cornstarch
Meringue:
4 jumbo egg whites
6 tablespoons sugar
1/2 teaspoon cream of tartar
In a saucepan, combine milk and sugar. Heat on medium. Blend the chocolate in just enough warm water to dissolve and add the beaten eggs. Blend cornstarch in just enough cold water to dissolve and mix with the cocoa and egg mixture. (This prevents your having lumps or scrambled eggs in the pudding!) Gradually pour the cocoa mixture into the heated milk. Add the vanilla. Stir constantly, until thickened. If it should become lumpy, try beating it with a mixer.
To make the meringue: Beat the egg whites and cream of tartar, adding sugar a little at a time until it is dissolved and the meringue is stiff and glossy.
Pour the pudding in the toasted pie shell. Top with meringue. Place the pie in a heated oven on low broil and watch it constantly until it toasts golden brown. Serve room temperature or chilled.
Desserts, 2001