In a large mixing bowl, sift together flour, sugar, and salt. Set aside.
In a nonstick medium saucepan, heat the heavy cream and butter (but do not boil). When the cream is hot, carefully pour the cream into the sugar mixture. Stir the mixture until all of the sugar has dissolved. Place the cream mixture into the freezer for approximately 20 minutes, stirring occasionally, until it has cooled completely.
Pour the cooled cream mixture into the thawed pie crust. Being careful not to spill the cream mixture out of the pie, transfer to a preheated oven and bake for 425°F for 15 minutes.
Reduce the oven temperature to 350°F and bake an additional 50 minutes.* Remove pie from oven and allow to cool in the fridge for at least 1 hour before serving.
In order to keep the crust from burning, create a ring of aluminum foil to cover the crust during the last 50 minutes of baking.