Preheat oven to 250°F. Line the bottom of a 9" springform pan with parchment or waxed paper, cut to fit.
Place the gingersnap cookies into a food processor and pulse until finely ground. Or, place the cookies into a large zip-top bag and crush with a rolling pin. In a medium bowl, combine the cookie crumbs, granulated sugar and melted butter. Stir to combine and press into the bottom of the pan; set aside.
In a small bowl, combine 2 cups powdered sugar, flour and nutmeg; set aside.
Add the cream cheese to a large mixer bowl; beat until smooth using the paddle attachment. Add the eggs and egg yolk and mix until smooth. Add in 1½ cups of eggnog and mix until smooth, then fold in the combined dry ingredients. Pour the cream cheese filling into the pan. Place the pan into the oven and bake for 1½ to 2 hours or until the filling is set. Let cool for at least an hour, then refrigerate to chill completely.
Prior to serving, combine the whipping cream and ¼ cup powdered sugar in a medium bowl and whip until stiff peaks form. Fold in 1/4 cup of eggnog and spread the whipped cream over the top of the chilled cheesecake. Decorate the cheesecake with fresh berries and chocolates or leave plain. Serve with freshley brewed Kona or Ka'u Coffee.