Preheat oven to 350 degrees F (180 degrees C). Line a muffin pan with cupcake liners.
In a medium bowl, combine the flour, baking powder, baking soda, salt, and nutmeg with a whisk.
In the bowl of a stand mixer fitted with the paddle attachment, cream the butter and sugar until light in color and fluffy, about 3–4 minutes. Add the vanilla extract and eggnog and mix until well combined.
Beat in the eggs one at a time.
Gradually mix in the dry ingredients until just combined, being careful not to over-mix.
Fill the prepared muffin tins with cupcake batter, about 2/3 full.
Bake in the middle of the oven for 20–22 minutes, or until a toothpick comes out clean when inserted into the middle of one of the cupcakes. Set aside to cool.
Make the eggnog buttercream according to the recipe. Fill a pastry bag fitted with a piping tip with the eggnog buttercream. Pipe the frosting on each cupcake. Sprinkle the cupcakes with sprinkles or a light dusting of ground nutmeg.