In a saucepan, cook brown sugar and butter until bubbly and caramelized. Whisk in scalded cream and milk to dissolve the sugar (creating butterscotch). In a bowl, beat egg yolks with cornstarch; temper with hot mixture. Return all to heat and cook until thickened, stirring constantly. Stir in vanilla and a pinch of salt. Pour filling into a prebaked pie crust. Cool completely until set. Top with whipped cream to serve..