Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans or line them with baking paper.
In a mixing bowl, cream the softened butter and granulated sugar together using an electric mixer on medium speed until light and fluffy, about 3-4 minutes.
Add the eggs one at a time, mixing well after each addition. Then stir in the vanilla extract and eggnog.
In a separate bowl, whisk together the flour, baking powder, baking soda, salt, ground nutmeg, and cinnamon.
Gradually add the dry ingredients to the wet mixture, mixing until just combined. Be careful not to overmix.
Divide the batter evenly between the prepared cake pans.
Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted in the center comes out clean.
Once baked, remove the cakes from the oven and allow them to cool in the pans for about 10 minutes, then transfer them to a wire rack to cool completely.
For the frosting, beat the softened butter with an electric mixer until creamy. Gradually add the powdered sugar and mix until smooth.
Pour in the eggnog and vanilla extract, then mix until well combined and fluffy.
Once the cakes are completely cool, place one layer on a serving plate and spread a layer of frosting on top. Place the second layer on top and frost the entire cake.
Optionally, sprinkle ground nutmeg on top for garnish before serving.