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 until well blended.
03 - In a large bowl, beat butter and sugar until light and fluffy, approximately 2–3 minutes.
04 - Add eggs one at a time, beating thoroughly after each addition. Mix in lemon zest, lemon juice, Limoncello, and vanilla extract until combined.
05 - Add dry ingredients in three alternating portions with milk, beginning and ending with dry mixture. Mix only until just incorporated to prevent tough texture.
06 - Distribute batter evenly among prepared liners, filling each approximately two-thirds full.
07 - Bake for 18–20 minutes until a toothpick inserted in the center emerges clean. Cool in pan for 5 minutes, then transfer to wire rack to cool completely.
08 - Beat butter until creamy. Gradually incorporate powdered sugar until smooth. Add Limoncello, lemon juice, lemon zest, and salt. Beat until light and fluffy, 2–3 minutes.
09 - Once cupcakes are completely cooled, frost with Limoncello frosting. Garnish with additional lemon zest if desired.