Preheat oven to 350°F and spray a cake pan with cooking spray.
Cream butter and sugar in the bowl in a stand mixer.
Combine flour, baking powder and salt in a medium bowl.
Add eggs to the stand mixer, one at a time, and beat after each addition.
In a container, combine the buttermilk and vanilla.
Alternately add the dry ingredients and the liquid ingredients to the batter, beginning and ending with the dry ingredients.
Fill cake pan about halfway up with the batter.
Bake for 20-22 minutes, until tooth pick inserted in the middle of a cupcake comes out clean.
Allow to cool 10 minutes in pan before transferring to a cooking rack.