Step 1

In the bowl of an electric stand mixer, using the paddle or whisk attachment whip butter on medium-high speed (if using whisk attachment whip on high speed) until nearly white and very fluffy, about 7 - 8 minutes, frequently scraping down the sides of the bowl.

Step 2

Add in powdered sugar, heavy cream, and vanilla extract and mix on low speed until blended. Then increase speed to medium and beat until very light and fluffy, about 5 - 6 minutes, frequently scraping down the sides of the bowl. Immediately spread over cooled cake or cupcakes.