Prepare cupcake tins with paper liners. Preheat oven to 350º F (175º C)
Place the flour, baking powder and salt in a large bowl; set aside.
In a large bowl (preferably in a stand mixer), cream the butter and sugar, slowly for 2 minutes. Increase to high and beat for another 4 minutes, or until light and fluffy, scraping the bowl occasionally. Add the 2 of the eggs, one at a time, clearing after each addition, then add half of the flour mixture, scraping the sides with a spatula if needed.
Add half of the buttermilk and mix well, then add another egg. Continue to mix; then add the remaining milk, egg, vanilla, vodka, Kahlua and flour. Scrape the bowl with a spatula at least once, and turn off once combined.
Fill the cupcake liners half full with the batter and bake for 25 to 30 minutes or until a skewer comes out clean when placed in the center of a cupcake. Place on cooling rack and allow to cool completely.
Meanwhile, make the icing, by beating all the ingredients until smooth. When the cupcakes are cool, cut the tops off if they are too tall.