Simple Buttercream Frosting

Mix with hand mixer:

1 stick (0.5 cup) well softened butter, room temperature or a little warmer,
but not liquid! Beat it for a while, until it is completely smooth,
and a little whipped up.

Add, a bit at a time, alternating:

one 1 lb. box of confectioners sugar

0.25 cup milk or buttermilk (preferred) (microwave to lukewarm)
a good dash of vanilla (use artificial clear vanilla if you
want the frosting to be as white as possible)

Mix until completely smooth. Be patient. You can add more confectioners
sugar if you want it to be thicker.
I was once told by a professional that you want it to be the
consistency of mayonnaise, but I think this is too thin.

Mix in colors at this point, if desired.