Using the whisk attachment of your stand mixer, whip the butter on medium-high speed for 5 minutes, stopping to scrape the bowl once or twice.
Reduce the speed to low and gradually add the powdered sugar. Once all of the powdered sugar is incorporated, increase the speed to medium-high and add the vanilla, mixing until incorporated. Whip at medium-high speed until light and fluffy, about 2 minutes, scraping the bowl as needed. Frost cake or cupcakes as desired.
Yield: This is enough frosting to generously frost 12 cupcakes or a 9x13-inch cake. If you are making 24 cupcakes or need to fill and frost a 2-layer cake, I recommend doubling the recipe.
Equipment: While a stand mixer with a whisk attachment makes this easy and efficient, you can also use a hand mixer.
Vanilla: You can substitute an equal amount of vanilla bean paste or the seeds from one vanilla bean for the vanilla extract.