Let the butter soften to room temperature
Cut the butter into small pieces
Place the butter in a mixing bowl
Add the sugar to the butter
Use a sturdy wooden spoon, spatula, or fork
Press the butter and sugar together against the side of the bowl
Mash, smear, and stir repeatedly
Scrape down the bowl often
Keep mixing until the mixture looks lighter in color
Continue until it becomes fluffy and smooth
Stop when the sugar is mostly dissolved and the texture is creamy