You can soften butter with a plastic bag and a rolling pin, but that requires some muscle power and only gives you soft butter, not room temperature butter. The One Pot Chef's shares an easier, quicker method.
Cut the amount of butter you want to use and put it on a plate. Grab a glass and fill it with hot water. Let it rest for a minute or till the glass outside is warm. In quick succession, tip the water out of the glass, dry it and invert it over the chunk of butter. In a minute or so, you'll have beautifully soft butter. Check out the video above to see it in action.
Quick Tips: Softening Butter in Moments [OnePotChefShow]