This mixing or beating technique not only combines ingredients to make a uniform mixture, but also incorporates air into this mixture. A whisk, wooden spoon, or electric mixer with paddle attachment can be used. The butter should be at room temperature so it incorporates the sugar sufficiently to produce a smooth and creamy batter that is light and fluffy. Follow your recipe's instructions, as this step can vary in length from seconds to minutes, depending on how much air needs to be incorporated into the batter so it rises properly in the oven.