Preheat oven to 350° F. Line muffin tin with paper liners (12-15 regular size); set aside
In bowl of electric mixer, beat butter and sugar together on medium-high speed until light and fluffy (2-3 minutes). Scrape bowl as needed.
Add eggs and vanilla. Beat on medium-high speed for 2 minutes. Scrape bowl as needed. Set aside
In a medium bowl, stir together flour, baking powder, and salt. Slowly add the dry ingredients to the batter in 3 additions, beating on low speed after each addition. The batter will be thick.
On low speed, add in milk, lemon zest, and lemon juice. Stir just until combined. Do not overmix the batter.
Spoon into cupcake lines, about 2/3 full. Bake 18-22 minutes, or until the top springs back when touched or toothpick inserted in center comes out clean.
Remove from oven and allow to cool completely before frosting.