How to Make It
Prepare the Piecrust: Pulse flour, granulated sugar, salt, and butter pieces in a food processor until mixture resembles coarse sand. While pulsing, add ice water, 1 tablespoon at a time, through food chute, just until mixture can be pressed together with fingertips. Form dough into a disk, and wrap with plastic wrap. Chill 1 hour.
Preheat oven to 400°F. Unwrap dough, and roll into a 12-inch circle on a lightly floured surface. Fit piecrust into a 9-inch pie pan, and trim, allowing 1/2 inch to extend over edge. Fold edge under, and crimp. Freeze 15 minutes.
Line piecrust with parchment paper, and fill completely with pie weights or dried beans. Bake in preheated oven until the crust is set and edge is light brown, about 15 minutes. Remove from oven; remove weights and parchment. Return to oven, and bake until golden brown, about 15 minutes. (If necessary, shield edges with aluminum foil after 10 minutes to prevent excessive browning.) Remove piecrust from oven, and cool completely on a wire rack, about 1 hour.
Prepare the Caramel Sauce: Bring granulated sugar and water to a boil in a medium saucepan over high. Cook, without stirring, until mixture is a deep amber color, about9 minutes. Remove from heat. Using a long-handled whisk and shielding hands from the steam, gradually whisk in cream until smooth. Whisk in whiskey and salt, and cool 30 minutes. (Mixture will thicken as it cools.) Store cooled Caramel Sauce in an airtight container in the refrigerator for up to 1 month.
Prepare the Filling: Whisk together egg yolks, cornstarch, and 1/4 cup of the half-and-half in a medium bowl. Set aside.
Stir together brown sugar, salt, and remaining 1 1/2 cups half-and-half in a large saucepan. Bring to a boil over medium-high, and remove from heat. Slowly whisk hot brown sugar mixture into egg yolk mixture; return mixture to saucepan. Cook over medium-high, whisking constantly and making sure to reach all points in the bottom of the saucepan, until mixture comes to a boil. Boil, whisking constantly, 1 minute. (Mixture will be very thick and smooth.) Remove from heat, and whisk in butter pieces, whiskey, and vanilla. Cool 30 minutes. Spoon filling into cooled piecrust. Chill until filling is firm and cold, about 4 hours.
Prepare the Topping: About 1 hour before serving, beat heavy cream and powdered sugar with an electric mixer on high speed until stiff peaks form, 3 to 5 minutes. (Do not overbeat.) Spread whipped cream over pie filling; chill 1 hour. Drizzle Caramel Sauce over pie.
For a smooth cut, dip the knife's blade into a glass of hot water and then wipe clean before using.