Preheat the oven to 350°F (175°C) and line a muffin tin with cupcake liners.

In a mixing bowl, cream together the softened butter and granulated sugar until light and fluffy.

Add the eggs, milk, lemon zest, and lemon juice, mixing until well combined.

In another bowl, whisk together the flour, baking powder, and salt.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

Divide the batter evenly among the cupcake liners, filling each about two-thirds full.

Bake in the preheated oven for 15-18 minutes, or until a toothpick inserted into the center comes out clean.

Allow the cupcakes to cool completely before frosting.

In a mixing bowl, beat the softened butter until creamy.

Gradually add the powdered sugar, mixing on low speed until combined.

Add the lemon juice, lemon zest, and vanilla extract, and beat until the frosting is light and fluffy.

Frost the cooled cupcakes with the lemon frosting using a spatula or piping bag.