Whisk together milk, eggs yolks and cornstarch until smooth.
In a medium sized saucepan, heat the cream until it is simmering, but not quit boiling.
Temper the eggs by SLOWLY pouring a small but stead stream of the hot cream in the egg mixture while whisking constantly. Whisk until smooth.
Return the mixture to the saucepan and cook over LOW heat, stirring constantly until the mixture thickens and no longer tastes "starchy". (this will be about 10-15 minutes)
Remove from heat and add the vanilla and chocolate chips. Mix until smooth and pour into the baked pie shell.
Optional: Top with chocolate ganache, whipped cream and garnish with chocolate shavings if desired.
