Preheat oven to 350°F. Grease a 9x13-inch pan with nonstick cooking spray.
Prepare the cake batter according to the directions on the box.
Pour the batter into the prepared baking pan.
Bake the cake according to the instructions on the box for a 9x13 baking pan.
Remove the cake from the oven.
Using the end of a wooden spoon, poke holes all over the cake.
In a medium mixing bowl, whisk together the pudding mix and eggnog until well-combined.
Immediately pour the pudding all over the cake, allowing it to fill up the holes.
Place the cake into the fridge for an hour.
Spread the cool whip over the top of the cake.
Sprinkle the cinnamon and nutmeg over the top.
Notes
Yellow cake mix - A similar cake mix, like white or butter, will also work.
Ingredients to make the cake - different box cake mixes call for different ingredients to make the batter. Just follow the directions on the box.
Eggnog - Feel free to use whatever type of eggnog you prefer.
Cool whip - You can also use homemade whipped cream. If using homemade whipped cream, you'll need about 1 1/2-2 cups of prepared whipped cream. Homemade whipped cream won't hold up as well as cool whip, so you'll need to use the cake quickly.