Preheat the oven to 350 degrees F and grease a flour a 12 cup Bundt pan and set aside.
In a mixing bowl, whisk together the flour, baking powder, nutmeg and salt. Set aside.
In the bowl of a stand up mixer with a paddle attachment, beat together the butter and sugar on medium speed for 4-5 minutes until light and fluffy.
Reduce the speed on the mixer and add the eggs, one at a time until combined. Mix in the vanilla extract.
Reduce the speed on the mixer and gradually add in the flour mixture and eggnog. Rotate between adding each one until just combined.
Stir in the rum or brandy if using.
Pour the batter into the prepared baking pan and gently tap the pan on the counter a few times to remove any air bubbles from the batter.
Bake for 45-55 minutes until a toothpick inserted into the center of the cake comes out clean.
Let the cake cool in the pan for 10-15 minutes. Then carefully remove the cake from the pan on the wire rack to cool completely.