Preheat oven to 350°F and line muffin tin with liners
Cream butter and sugar until light and fluffy
Beat in eggs one at a time, then add vanilla
Whisk flour, baking powder, and salt in separate bowl
Alternate adding dry mix and milk into batter
Fold in flour-coated chocolate chips
Fill liners ⅔ full with batter
Bake 18–22 minutes, test with toothpick
Cool 5 minutes in pan, then transfer to rack