In a very large bowl, beat the cream cheese until soft. Turn down the mixer and scrape down the sides of the bowl as necessary.
Beat in the sugar, cornstarch and nutmeg.
Using a wire whisk, whisk in the rum/rum extract and eggnog.
In a small bowl, whisk together the eggs and additional egg yolks.
Whisk the eggs into the cheesecake batter, about 1/2 at a time. Keep whisking until you no loner see pieces of egg.
Place the cheesecake crust in the middle of a large roasting pan, then pour the cheesecake filling on top of the crust.
Pour the hot water into the roasting pan, so that there's about 1/2-1 inch of water in the bottom of the roasting pan.
Place the roasting pan with the cheesecake inside in the oven and bake for 50-60 minutes, or until the top looks almost set, except for in the very middle.
Remove from the oven. Cool the cheesecake in the water bath until room temperature.
Then remove the springform pan from the roasting pan, cover the cheesecake, and refrigerate for at least 6 hours. (Keep the cheesecake in the roasting pan).
When ready to serve, trace around the edges of the cheesecake with a very thin knife. Then unclamp the springform pan.
Optionally, sprinkle with a little extra nutmeg and dollop each slice with whipped cream.