Preheat your oven to 350°F (175°C) and line a cupcake tray with paper liners.

In a bowl, whisk together flour, cocoa powder, baking powder, and salt. Set aside.

In another bowl, beat softened butter and sugar until fluffy. Add eggs one at a time, followed by milk and Kahlúa; mix until smooth.

Gradually add dry ingredients to the wet mixture; stir until just combined.

Spoon batter into prepared liners and bake for 18–20 minutes or until a toothpick comes out clean.

For the frosting, beat softened butter until fluffy, gradually add powdered sugar and Kahlúa until desired consistency is achieved.

Frost cooled cupcakes generously with Kahlúa buttercream.