Prepare cake mix according to the directions with the ingredients above. Place cupcake wrappers in the pan and fill 3/4 full.
Before you put them in the oven, pick the pan up and drop it on the counter to remove any air bubbles. Bake according to the directions on the box. Remove from the oven and let cool before icing
For the Buttercream: Beat softened butter and 2 cups powdered sugar until smooth. Add milk or half and half and vanilla. Continue adding powdered sugar until the right consistency. It is very forgiving if you add to much powdered sugar you can add another splash of milk.
If I am using a piping bag I like the icing a little looser and fluffier than when I frost by hand, so I mix it a little longer and add a splash more milk.