We don’t know about you, but we almost never remember to set butter out ahead of time so that it can soften. This is a real pain because it takes roughly an hour for butter to properly soften.
However, the more surface area you have the faster this process can take place. Two tricks to achieving more surface area is to either grate your butter or you can place it in a plastic bag and flatten it with a rolling pin.
SOURCE: Bigchill.com