Preheat your oven to 350°F (175°C). Grease and flour the baking pan to prevent sticking.
In a large mixing bowl, combine the flour, baking powder, nutmeg, and salt. Set aside.
In another bowl, use an electric mixer to cream the softened butter and granulated sugar until light and fluffy.
Add the eggs one at a time, mixing well after each addition. Then add the vanilla extract and eggnog, and mix until combined.
Gradually add the dry ingredients to the wet mixture, mixing just until combined. Do not overmix.
Pour the batter into the prepared baking pan and spread it evenly.
Bake in the preheated oven for 30-35 minutes, or until a toothpick inserted into the center comes out clean.
Once baked, remove from the oven and allow the cake to cool in the pan for about 10 minutes. Then transfer to a cooling rack to cool completely.
For the frosting, beat the softened butter in a bowl until creamy. Gradually add the powdered sugar, alternately mixing in the eggnog and vanilla extract until the desired consistency is reached.
Once the cake is completely cool, spread the frosting evenly over the top. Sprinkle the ground nutmeg on top for garnish.
Slice, serve, and enjoy your delicious Eggnog Cake!