Preheat the oven to 375°F and line a 12-cup muffin tray with paper liners.
In a stand mixer, beat the butter and sugar on medium speed until light and fluffy.
Add the egg, vanilla extract, and milk, mixing until smooth.
In a separate bowl, sift together the flour, baking powder, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing on the lowest speed until just combined.
Using an ice cream scoop or spoon, fill the muffin cups ⅔ full.
Bake for 18-20 minutes, or until a toothpick inserted in the center comes out clean.
Let the cupcakes cool completely before frosting.