In the bowl of an electric stand mixer, whip the butter on medium-high speed until nearly white and very fluffy, about 7-8 minutes, scraping down the sides of the bowl as needed.

Add powdered sugar, heavy cream, and vanilla extract. Mix on low speed until blended, then increase to medium speed and beat until very light and fluffy, about 5-6 minutes.

Immediately spread the frosting over cooled cakes or cupcakes.