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

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

Add the eggs one at a time, beating well after each addition.

Mix in the lemon zest and lemon juice.

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

Gradually add the dry ingredients to the wet ingredients, alternating with the milk until combined.

Fill the cupcake liners about 2/3 full with batter and bake for 18-20 minutes or until a toothpick comes out clean.

In a medium bowl, cream together the softened butter and powdered sugar until smooth.

Add the fresh lemon juice and lemon zest, and mix until well combined.

Once the cupcakes are completely cooled, frost them with the lemon frosting.