First, start by lining your springform cake pan with a disc of non-stick baking paper. Then, you can brush the sides of the pan with melted butter or spray it with non-stick cooking spray.
Then, crush the Graham crackers until they form a fine uniform crumb. You can also use a food processor to make your life easier. Once you have crumbs, combine them with the rest of the crumb ingredients in a large bowl. Again, mix until the crumbs are uniform in texture.
Finally, press the mixture into your lined springform cake pan. You can use the back of a flat measuring cup or mug to pack in the crumbs. They should be tightly pressed inside the pan.
Then, place the entire cake pan inside the fridge so that the crust can start setting in place.
In a large mixing bowl, cream together the softened cream cheese and caster sugar. The sugar should be completely dissolved and the mixture should be fluffy and lump-free. Then, whisk in the ground cinnamon and nutmeg, salt, and extract (if you are using any).
Next, using medium speed, slowly whisk in the eggnog. Keep whisking until the mixture is completely lump-free and uniform in texture.
Lastly, whisk in the melted cooled white chocolate. Make sure to scrape down the bowls to ensure you incorporate all of the ingredients evenly.
Once your filling is made, gently pour it into the crust-lined cake pan. Then, wrap the entire pan with plastic wrap and place it in the fridge. Allow it to set for at least 8 hours, but preferably overnight.