In saucepan, combine sugar, flour, and salt
Gradually stir in milk
Cook and stir over medium heat until bubbly
Cook until thickened (around 5 minutes), stirring constantly to prevent burning
Remove from heat
Add butter and vanilla
Mix in dark chocolate chips
Pour into pastry shell
Refrigerate until cooled
Whip 2 cups heavy cream until thickened
Add ¾ cup powdered sugar to whipped cream
Top cooled pie with whipped cream and chocolate shreds
Serve
