In a stand mixer or hand held mixer, beat butter until fluffy, 2-3 minutes.
Add powdered sugar 1/4 cup at a time. Mix until well combined. Use a spatula to clean edges of the mixing bowl to make sure all powdered sugar is mixed together.
Next add in the heavy whipping cream, vanilla & salt. Mix well. This is when you can add in more powdered sugar if the frosting is too thin, or add in more heavy cream if the frosting is too thick. Add in food coloring if you want colored frosting.
Add frosting to a piping bag or bottle, or spread onto cookies & frost!