In a medium bowl, thoroughly mix the pudding mix, milk, eggnog, nutmeg and cinnamon until smooth. Fold in one 8-ounce tub of whipped topping until thoroughly combined.
Arrange a single layer of graham cracker squares in the bottom of a 13×9 inch baking pan. Having a little bit of space between the graham crackers is totally fine.
Evenly spread half of the pudding mixture over the graham crackers. Top with another layer of graham crackers and the remaining pudding mixture. Top with a final layer of graham crackers.
Spread the remaining 2 cups of whipped topping onto the top of the cake. Cover and chill for at least 4 hours.