How to Make It
In a small saucepan, combine half the cream, the chocolate, and 3 tablespoons of the sugar. Cook over medium-low heat, whisking frequently, until the chocolate melts. In a bowl, combine the cornstarch and the remaining sugar. Add the egg yolks and whisk.
Add 2 tablespoons of the warm chocolate mixture to the egg mixture. Whisking constantly, slowly add the egg mixture to the pan. Cook, still whisking, until thickened, 2 minutes. Remove from heat. Add the vanilla and butter. Whisk until the butter melts.
Pour the filling into Shortbread-Pecan Crust. Place a piece of plastic wrap directly against the surface of the filling. Refrigerate for at least 3 hours and up to 48 hours. Sprinkle with the cocoa. With an electric mixer on medium-high, beat the remaining cream. Serve with the pie.