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

In a medium bowl, whisk together flour, baking powder, and salt.

In a large bowl, cream together butter and sugar until light and fluffy. Beat in eggs one at a time, then stir in vanilla.

Gradually add the dry ingredients to the wet ingredients, alternating with milk, beginning and ending with dry ingredients. Mix until just combined.

Fill cupcake liners 2/3 full.

Bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean.

Let cool in the muffin tin for 5 minutes before transferring to a wire rack to cool completely.

In a large bowl, beat butter until light and fluffy. Gradually add powdered sugar, beating until smooth.

Stir in milk and vanilla extract until smooth and creamy.

Frost cooled cupcakes with frosting.