Preheat oven to 325°F. Line a 9x13-inch baking pan with parchment paper, leaving overhang on the long sides for easy lifting.
In a bowl, combine graham cracker crumbs, sugar, and cinnamon.
Stir in melted butter until evenly coated.
Press firmly into the bottom of the prepared pan.
Bake for 10 minutes, then remove and let cool slightly.
In a large mixing bowl, beat softened cream cheese until smooth and creamy.
Add sugar and mix until combined.
Add eggs one at a time, mixing just until incorporated after each.
Add eggnog, flour, vanilla, nutmeg, cinnamon, and salt. Mix on low just until smooth. Do not overmix.
Pour filling over the crust and smooth the top.
Bake for 40–50 minutes, or until the center is just set (not glossy or wiggly).
Turn off the oven, crack the door, and let the cheesecake cool in the oven for 20–30 minutes.
Cool completely at room temperature, then refrigerate for at least 3 hours.
Lift out using parchment overhang, slice into bars, and top as desired.
