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, mixing well after each addition. Stir in lemon zest and lemon juice.

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

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

Spoon the batter into the prepared muffin tin, filling each cup about two-thirds full.

Bake for 15-18 minutes or until a toothpick inserted into the center comes out clean. Allow to cool.

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

Gradually add the powdered sugar, beating until well combined.

Mix in lemon juice and vanilla extract until the frosting is smooth and fluffy.

Once the cupcakes are completely cool, spread or pipe the lemon frosting on top.

Optionally, garnish with additional lemon zest or a slice of lemon.