Pre-bake pie crust and set aside to cool.
Place the chopped chocolate, butter, and vanilla extract in a mixing bowl and set aside. In a medium saucepan, whisk together the sugar, cornstarch, cocoa, and salt. Whisk in 1/2 cup of cold heavy cream until the mixture is smooth. Repeat with another 1/2 cup of the cream.
Whisk in the egg yolks. Place the saucepan over medium heat, and gradually whisk in the whole milk. Bring to a boil, whisking constantly. Let boil for 1-2 minutes or until it begins to thicken.
Remove the pan from the heat and pour the mixture over the chocolate and butter. Whisk until the chocolate is melted and the mixture is silky smooth. Place plastic wrap on the surface of the custard to prevent a skin from forming, and chill for 3-4 hours. The chilling is important as it allows it to thicken.
In a medium saucepan, heat butter, brown sugar, evaporated milk, and egg yolks over medium heat. Whisk the mixture together and watch for it to boil. Once it begins to boil, let it boil for 5-6 minutes, whisking constantly. The mixture should begin to thicken. Remove from heat.
Add vanilla, coconut, and pecans and fold together. Set aside to cool to room temperature or place in the refrigerator to cool.
Beat 1-2 cups of heavy cream (depending on how much whipped cream you desire) and add 1/4 cup of powdered sugar and beat until soft peaks form. Fold in vanilla. Top each slice with whipped cream.
Fill the baked pie crust with chocolate custard filling. Spread evenly into the crust. Top with coconut pecan filling and carefully spread over chocolate custard. Place in the refrigerator and let chill until ready to serve, at least 30 minutes. I prefer to make sure the pie is very firm. Serve with fresh whipped cream and chocolate shavings.
*Make sure to use EVAPORATED milk (not sweetened condensed milk). Evaporated milk can be found in a can in the baking aisle.
** You may also use your favorite chocolate or graham cracker crust. My recipes are linked in the body of this recipe post.