Preheat the oven to 350 degrees. Line one cupcake pan with paper liners. Set aside.
Whisk together the flour, baking powder, salt, cinnamon, and nutmeg. Set aside.
Place the butter and sugar in the bowl of an electric mixer. Beat, with the paddle attachment, for two minutes or until light and fluffy. Scrape the sides of the bowl.
Add the eggs, one at a time, until incorporated into the batter. Stir in the vanilla.
Add the dry ingredients along with the buttermilk. Stir on low until just combined.
Divide the batter between your prepared liners, filling 2/3 full. Bake 10-15 minutes or until a toothpick comes out clean.
For the Frosting:
Place the butter into the bowl of an electric mixer. Beat with the whisk attachment for two minutes or until fluffy.
Mix in the remaining ingredients, beating for two to three minutes, until fully combined and frosting is fluffy. Pipe or spread onto cooled cupcakes.