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