In a mixing bowl, combine graham cracker crumbs, granulated sugar, and melted butter until it resembles wet sand. Firmly press this crumb mixture into a greased 9-inch pie pan, ensuring an even layer across the bottom and up the sides. Chill the crust in the refrigerator for 30 minutes to allow it to set.

In a large bowl, beat the softened cream cheese and powdered sugar together until smooth and creamy. Gradually mix in the eggnog, ground nutmeg, and ground cinnamon, blending well to incorporate the spices fully. Gently fold in the whipped cream until the mixture is light and fluffy.

Pour the creamy filling into the chilled graham cracker crust, smoothing the top with a spatula for an even finish. Cover the pie with plastic wrap or a lid, then refrigerate for at least 4 hours to allow it to set properly and develop its rich flavors.

Once the pie has set, remove it from the refrigerator and top it generously with whipped cream. Sprinkle additional nutmeg on top for a festive garnish that enhances both flavor and presentation.