Preheat your oven to 350°F (175°C) and line a muffin tin with cupcake liners.
In a mixing bowl, cream together the butter and sugar until light and fluffy.
Add the eggs one at a time, beating well after each addition.
Mix in the coffee and whiskey.
In a separate bowl, whisk together the flour, baking powder, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Divide the batter evenly among the cupcake liners, filling each about ⅔ full.
Bake for 20-25 minutes, or until a toothpick inserted into the center comes out clean.
Let the cupcakes cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.
For the frosting, beat the butter until creamy, then gradually add the powdered sugar and Irish cream liqueur, beating until smooth.
Frost the cooled cupcakes and enjoy!