01 - Preheat oven to 350°F. Line a 12-cup muffin tin with paper liners.
02 - In a medium bowl, whisk together flour, baking powder, and salt. Set aside.
03 - In a large bowl, beat the butter and sugar until light and fluffy, approximately 2 to 3 minutes.
04 - Add eggs one at a time, beating well after each addition. Mix in vanilla extract.
05 - Combine alcohol-free Irish cream and milk in a small bowl or measuring cup.
06 - With mixer on low speed, add the flour mixture to the wet ingredients in three additions, alternating with the Irish cream and milk mixture, beginning and ending with flour. Mix until just combined.
07 - Divide batter evenly among cupcake liners, filling each approximately two-thirds full.
08 - Bake for 16 to 18 minutes, or until a toothpick inserted in the center comes out clean. Cool in pan for 5 minutes, then transfer to a wire rack to cool completely.
09 - Beat the butter on medium speed until creamy, approximately 2 minutes. Add powdered sugar gradually, beating until smooth. Mix in alcohol-free Irish cream, vanilla, and salt. Beat for 1 to 2 minutes until fluffy.
10 - Once cupcakes are completely cool, frost with Irish cream buttercream using a piping bag or spatula.