Preheat your oven to 350°F (175°C) and line a cupcake tray with paper liners.
In a mixing bowl, cream together butter and sugar until light and fluffy.
Add eggs one at a time, mixing well after each addition.
Stir in lemon zest and lemon juice.
In a separate bowl, combine flour, baking powder, and salt.
Gradually add dry ingredients to the wet mixture, alternating with milk.
Divide the batter evenly among the cupcake liners.
Bake for 15-20 minutes, or until a toothpick inserted comes out clean.
Allow cupcakes to cool completely before frosting.
Frost with lemon buttercream and serve.