Make, pre-bake, and set aside the crust to cool.
Place sugar, flour, gelatin, and salt in a medium saucepan and mix with a whisk or a fork.
Whisk in the half-and-half gradually.
Turn the heat to medium and stir in a figure-eight pattern, until it comes to a boil. Let it boil for 1 minute, while stirring. Remove from the heat and pour into a large bowl.
Stir in the whiskey. Let cool.
In a stand mixer or bowl with a hand mixer, beat the egg whites until soft peaks form. Add the cream of tartar while continuing to beat until stiff peaks form. Set aside.
Pour the whipping cream into a deep metal bowl that has been chilling in the freezer. Beat in a stand mixer or in a bowl with a hand mixer, until the cream makes stiff peaks. Set aside.
Fold the beaten egg whites into the cooled filling.
Carefully fold the whipped cream into the filling.
Turn the filling into the pre-baked pie shell. Place in the fridge and let set for 3 to 4 hours, although overnight is best.
Make the Boozy Whip and pipe it around the edge in a pleasing pattern, or spread over the top of the pie. Sprinkle the top with grated nutmeg.