Place butter in bowl of mixer and attach flat paddle beater. Mix on medium speed until butter breaks up and is starting to look smooth.
Add vanilla and salt; mix for 30 seconds until combined. If you decide to add butter flavoring, omit the vanilla.
Add in heavy whipping cream.
Measure powdered sugar on scale. Slowly add powdered sugar to mixer, one cup at a time.
PRO TIP: Start the mixer speed back up slowly after adding the cup of powdered sugar, otherwise, you'll be doing some cleaning, too.
Once ingredients are all mixed, turn the mixer to medium high and set timer for five minutes.
Flavor or color the buttercream to your preference.