Preheat oven to 400 degrees.

Brush pie shell lightly with reserved egg whites.

Bake crust until light golden brown.

Set aside to cool.

In medium saucepan, stir cocoa powder, flour, sugar and salt.

Add egg yolks and milk. Stir to combine.

Over medium heat, cook filling until thickened.

When thick, remove from heat and add butter and vanilla.

Pour into cooled pie crust.

With mixer, beat egg whites until stiff peaks form.

You can add couple of spoons of sugar if you like. And teaspoon cream of tartar.

Pile meringue onto hot filling and cover edges to seal.

Broil for a few minutes to brown meringue to your desired darkness.

Let pie cool completely before slicing.

Store covered in fridge.

Enjoy :)