Preheat your oven to 350°F (175°C) and line a muffin tin with cupcake liners.
In a mixing bowl, whisk together the flour, baking powder, and salt.
In another bowl, beat the butter and sugar until light and fluffy. Add the eggs one at a time, beating well after each addition.
Mix in the lemon juice and zest. Gradually add the dry ingredients, alternating with the milk, beginning and ending with the dry ingredients.
Divide the batter evenly among the cupcake liners, filling each about ⅔ full. Bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean. Let cool completely.
For the frosting, beat the butter until creamy. Gradually add the powdered sugar, lemon juice, and zest, beating until smooth and fluffy.
Frost the cooled cupcakes and enjoy!