Whip the butter and salt for about a minute using a stand mixer fitted with a paddle attachment. You can use a hand mixer instead if needed.
Sift in the confectioner’s sugar in several batches beating on low after each addition. Scrape the bowl down and repeat the process.
Add a tablespoon of the cream while mixing on low then add the vanilla. Beat until you have an even, fluffy consistency. You can add more cream or milk if desired for a thinner consistency.
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Notes
Sift your powdered sugar to avoid clogging piping tips.
Scrape the bowl down; to help ensure even consistency throughout.
You can use almost anything to flavor buttercream, fruit juice, coffee, orange blossom or rose water, melted chocolate, or Oreos!
If your buttercream has been sitting for a while or was chilled and brought back to room temperature it's always a good idea to give it a quick whip to restore it's consistency.
If you're looking for a very spreadable and very smooth icing, you can add the full amount of cream in (and maybe even a bit more).