In a large saucepan, over medium heat, add sugar, flour, cornstarch and salt.
Slowly add milk, constantly stirring until it thickens.
In a separate bowl, temper 2 egg yolks by whisking in a small amount of hot mixture to bowl.
Whisk in the eggs and add the butter and vanilla.
Allow to cook for a few minutes.
Pour into a dish and refrigerate, allowing to cool.
When ready, fill pie shell with butterscotch mixture.
Using a hand mixer, whip together the heavy cream and sugar until light and fluffy.
Mix the butterscotch morsels into the whipped cream.
Cover pie with whipped cream mixture and garnish with more butterscotch morsels.
