In a large mixing bowl, beat the butter on medium speed until it's pale, light, and fluffy (about 5 minutes).
Add the powdered sugar gradually, 1 cup at a time, beating well after each addition.
Pour in the heavy cream, vanilla extract, and a pinch of salt.
Beat the mixture on medium-high for an additional 3-5 minutes until it’s smooth and fluffy.
Use immediately or refrigerate and re-whip before using.