In a standing mixer fitted with the paddle attachment, beat together butter and sugars on medium speed until light and fluffy, about 3 minutes. Scrape down the sides and bottom of the bowl as necessary. Add eggs, one at a time, beating well after each addition. Beat in vanilla extract. Reduce mixer speed to low and add half of the dry ingredients, beating just until combined. Add milk and beat until combined. Add the other half of the dry ingredients and beat slowly only until combined. Do not over mix—the less you mix, the lighter the cupcakes will be.