In a microwave-safe mug or bowl, sprinkle the gelatin over the water. Set aside for 5 minutes.
In the bowl of a stand mixer fitted with the paddle attachment or large mixing bowl with a hand mixer, add the room temperature cream cheese. Mix on low speed for 2 minutes or until smooth. Add the sugar, cinnamon, and nutmeg. Mix on medium-low for another 2 to 3 minutes or until smooth. Stop the mixer and scrape down the sides and bottom of the bowl.
Zap the gelatin mixture in the microwave for about 15 seconds. The gelatin should be liquid but not too hot. Stir the liquid gelatin mixture into the eggnog.
With the mixer on low, slowly pour the eggnog into the cream cheese mixture. Add the vanilla and mix until combined. Scrape the cream cheese mixture into a large bowl and set aside.
In a cleaned bowl of a stand mixer fitted with the paddle attachment or a separate bowl with a hand mixer and whisk, add the heavy cream. Whip on medium-high until medium peaks form.
Stop the mixer and fold half of the whipped cream into the cream cheese mixture. Once incorporated, fold in the remaining whipped cream until thoroughly combined.
Spoon the cheesecake filling into the chilled crust. Smooth out the top with the back of a spoon or an offset spatula. Chill in the refrigerator for at least 3 hours or overnight before slicing.
Before serving, run a thin knife around the inside of the springform pan. Carefully unlock the pan and remove the collar. Top with whipped cream and decorate as desired.