Beat the butter until smooth and creamy in the bowl of a stand mixer fitted with the paddle attachment. (approx 2-3 minutes)
Gradually mix in the confectioner’s sugar, working slowly to keep it from flying out of the bowl.
Continue mixing, and add the heavy cream, vanilla extract, and salt.
Increase the speed of the mixer and beat the frosting well for 60-90 seconds.
If you are adding food color, this would be the time to do so. Make sure you let it mix well after each drop addition, keeping in mind that the color will intensify as the frosting sits.
Notes
NOTE: For a firmer frosting that will crust as it sits (making the cookies stackable) use less cream. For creamier frosting, use milk instead of heavy cream.Store at room temperature for 2-3 days on decorated cookies or keep refrigerated for up to 1 week.