Preheat your oven to 350°F (175°C).
In a medium saucepan, combine the eggnog, heavy cream, eggs, granulated sugar, cornstarch, vanilla extract, nutmeg, and salt. Whisk together until well combined.
Place the saucepan over medium heat and cook the mixture, stirring continuously, until it thickens and begins to bubble, about 5-7 minutes.
Once thickened, remove from heat and pour the filling into the pre-made pie crust, smoothing the top with a rubber spatula.
Bake the pie in the preheated oven for about 10 minutes, just until the edges set.
Remove from the oven and let cool to room temperature.
Once cooled, refrigerate for at least 2 hours to set completely.
Serve chilled, topped with whipped cream and a sprinkle of nutmeg, if desired.