Make and bake a traditional roll-out pie crust, an easy shortcut no-roll pie crust, or a pecan nut pie crust.
Pre-heat the oven to 350°.
In a large (somewhat deeper) saucepan, mix together the sugar, corn starch, and salt.
Separate your egg yolks out (but save back 3 of your whites for the meringue pie topping).
Beat the egg yolks.
Beat together the egg yolks and heavy whipping cream.
Add the egg/cream mixture to the sugar mixture in your saucepan, and whisk everything together well.
Bring this mixture to a boil over medium heat, constantly stirring so the mixture doesn't scorch.
Once it comes to a boil, reduce the heat just a bit, and let it boil for maybe half a minute, constantly stirring.
Note: You don't want to boil it too long because if you do, an oil will form and start to separate from your mixture. If this happens, don't despair; it's totally fixable. Just pour as much of the oil off as much as possible without losing your filling, and your pie filling will be right as rain... No need to make a whole new filling.)
Remove the mixture from the heat.
Immediately whisk in the butter, vanilla, and cocoa powder. Mix well.
Pour the pie filling into your prepared and baked pie crust.
Top with meringue and bake at 350° for about 15 minutes, maybe a little longer, or until the meringue begins to turn a warm golden color.
Remove the pie from the oven, and cool for 1 hour, preferably on a wire rack.
Then refrigerate for at least a couple of hours before serving. Also keep any leftover pie refrigerated.
Slice, serve, and enjoy!