Preheat your oven to 350°F (175°C). Grease and flour a 9x13 inch baking dish.
In a mixing bowl, combine the flour, sugar, baking powder, nutmeg, and cinnamon. Mix well.
In another bowl, beat the softened butter until creamy with an electric mixer. Add the eggs, eggnog, and vanilla extract, mixing until combined.
Gradually add the dry ingredients to the wet ingredients, mixing until just incorporated.
Pour the batter into the prepared baking dish, spreading it out evenly. Bake for 30 minutes or until a toothpick inserted in the center comes out clean.
Once baked, remove the cake from the oven and allow it to cool for about 10 minutes. Use a toothpick or skewer to poke holes all over the cake.
In a separate bowl, whisk together the vanilla pudding mix and 1 ½ cups of eggnog until combined. Slowly pour the mixture over the warm cake, ensuring it seeps into the holes.
Allow the cake to cool completely in the pan, then refrigerate for at least 2 hours to set the pudding.
Before serving, spread the whipped cream over the top of the cake and garnish with a sprinkle of ground nutmeg.
Slice, serve, and enjoy!