In a large bowl or stand mixer, cream butter with sugar. Mix in egg and vanilla, scraping bowl as needed. Add remaining dry cupcake ingredients, mixing until fully incorporated. Finally, slowly add in milk, mixing just until no streaks remain and batter is smooth. Using a large cookie scoop
, add one scoop to each liner. Bake for 18-20 minutes or until a toothpick inserted comes out clean. Cool in pan for 5 minutes, then transfer to a wire rack to cool completely.