Make the Cupcakes

1. Prepare a cupcake pan with cupcake liners and preheat the oven to 350°F (176°C).
2. Combine the flour, baking powder, nutmeg and salt in a medium-sized bowl and set aside.
3. Add the butter, sugar and oil to a large mixer bowl and beat together until light in color and fluffy, about 3 minutes. Do not skimp on the creaming time.
4. Add the eggs one at a time, mixing until mostly combined after each. Add the vanilla extract with the second egg. Scrape down the sides of the bowl as needed to be sure all ingredients are well incorporated.
5. Add half of the dry ingredients to the batter and mix until mostly combined.
6. Slowly add the eggnog and mix until well combined.
7. Add the remaining dry ingredients and mix until well combined and smooth. Scrape down the sides of the bowl as needed to be sure all ingredients are well incorporated. Do not over mix the batter.
8. Fill the cupcake liners just over 1/2 full and bake for 15-18 minutes or until a toothpick inserted into the center comes out clean.
9. Remove cupcakes from the oven and place cupcakes on a cooling rack to cool.

Make the Buttercream

1. Combine the butter and shortening in a large mixer bowl and mix until well combined.
2. Add 2 cups of powdered sugar and mix until well combined and smooth.
3. Add 2 tablespoons of eggnog, the rum extract, nutmeg and salt and mix until well combined and smooth.
4. Add the remaining powdered sugar and mix until well combined and smooth.
5. Add remaining eggnog and mix until well combined and smooth.
6. Frost the cupcakes with buttercream and sprinkle with a little nutmeg, if desired.