In a large saucepan, bring the cream and 1/4 cup of sugar up to 180℉ over medium heat, stirring very often. The mixture should be hot and start to steam across the top but should not boil.
While the cream is heating, mix the cornstarch and 1/4 cup of sugar together in a medium bowl.
Add the egg yolks and whole egg to the cornstarch mixture and whisk to combine well.
When the milk is hot, slowly whisk one cup of hot milk into the egg mixture and then whisk the egg mixture back into the pan of hot cream.
Cook over medium heat until the mixture starts to bubble and thicken, stirring constantly, about 6 minutes.
Remove from the heat and stir in the chocolate chips, butter, and vanilla.
Cover the pan and refrigerate until cool (about 2 to 4 hours).
When the chocolate pudding is cool and you are ready to assemble your pie, whip the heavy cream.
Place half of the chocolate pudding in the bottom of the pie crust and spread it out evenly.
Mix half of the whipped cream into the other half of the chocolate pudding and fold it together until the chocolate pudding is lighter in color and fluffy.
Add this chocolate and cream mixture to your prepared crust over the plain chocolate pudding and spread it around.
Add the remaining whipped cream to the top of the pie (you can spread it or pipe it out) and then top with chocolate curls.
Notes
You can use either heavy cream or heavy whipping cream in this recipe but stay away from regular whipping cream (the fat content isn’t as high and results in a less stable whipped cream).
When adding the filling to the pie crust, you can put all the pudding on the bottom of the pie and all of the cream on the top or make them into three layers like I did here.
To make chocolate curls, use a vegetable peeler down the side of a chocolate bar.