Cream the softened butter until smooth. Blend in the vanilla.
Add half of the powdered sugar, the salt, and most of the milk. Beat at medium speed until the powdered sugar is incorporated.
Add remaining powdered sugar and milk and mix at medium speed another 3 to 4 minutes scraping the sides of the bowl occasionally. Then, slow down the mixer to very slow for 1 to 2 minutes. This will help eliminate air pockets in the buttercream. The texture will become very smooth.
This recipe can be doubled or halved.
Yields approximately 4 ½ cups of frosting. Enough to frost a two layer 8 or 9 inch cake.
Can be frozen in air tight container for at least three months . Thaw on countertop.
If your buttercream is too thin, add more sugar. If the consistency is too thick, add a bit more milk.