Preheat the oven to 350˚F. Line muffin pans with paper liners and set aside.
In a medium bowl, mix together the flour, baking soda, baking powder, salt and nutmeg. Set aside.
In the bowl of a stand mixer, beat together the eggnog, oil, vinegar, vanilla and sugar until fully combined. Slowly mix in the dry ingredients until fully incorporated.
Divide the batter into the prepared cupcake liners and bake in the preheated oven for 22-24 minutes, or until a toothpick inserted comes out clean. Allow the cupcakes to cool in the pan for 5 minutes, then transfer to wire racks to cool completely.
Eggnog Buttercream: In the bowl of a stand mixer, cream the butter for around 30 seconds. Add in the powdered sugar and nutmeg, and mix until smooth. Add in the eggnog and beat until light and fluffy. Pipe the frosting onto the cooled cupcakes and top with sprinkles.