In a mixing bowl or bowl of an electric mixer, beat butter until smooth and creamy, about 2 minutes.
Add confectioners' sugar ½ cup at a time, mixing well and scraping down sides of bowl occasionally.
Beat in vanilla and salt; stir until smooth.
Notes
Nutrition is for 1 cup of frosting.Storage: Frosting will keep covered in the refrigerator for up to a week. Bring to room temperature and stir before using, if chilled.