Preheat the oven to 350°F and grease two 8" cake pans.
In a medium bowl, whisk the flour, baking powder, and salt together.
In a liquid measuring cup combine the buttermilk and Baileys. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment, cream together the butter and sugar on medium-high until light and fluffy – about 2 minutes.
Add eggs one at a time, fully incorporating after each addition. Add in the vanilla extract.
Turn the mixer down to medium and alternate adding the dry ingredients and buttermilk/Bailey's mixture, starting and ending with the dry ingredients. Be careful not to over-mix!
Distribute the batter into the pans and bake for 25-30 minutes or until a toothpick inserted in the center comes out clean. Let the cakes cool for about 10 minutes in the pan. Then transfer them to a wire rack to cool completely.