1. Preheat oven to 325 degrees. Lightly grease a 9 x 5 loaf pan and set aside.
  2. Place butter and cream cheese in a large bowl and cream on high until light and fluffy.
  3. Whisk together sugar, flour, salt and baking powder in a medium bowl; add to butter mixture and beat until well-combined. (It will look crumbly and sandy at first, but keep beating it until it resembles a somewhat dry cookie dough that clumps together.)
  4. Whisk together the eggs, vanilla and Irish Cream Liqueur in a small bowl. Add liquid to batter in 3 batches, beating well after each addition.
  5. Pour batter into prepared pan and bake for 55 minutes. Lightly tent pan with foil to keep from overbrowning and bake for another 25-35 minutes or until toothpick inserted in loaf comes out clean.
  6. Cool for 10 minutes in pan and then remove from pan to cool completely on wire rack.