With a handheld or stand mixer fitted with a paddle or whisk attachment, beat the butter on medium speed until creamy–about 2 minutes.
Add confectioners’ sugar, lemon juice, heavy cream, and zest with the mixer running on low.
Increase to high speed and beat for 3 minutes.
Taste and add salt as needed.
Add up to 1/2 cup more confectioners’ sugar if frosting is too thin or another tablespoon of cream if frosting is too thick.
Cover tightly and store for up to 1 week in the refrigerator or up to 3 months in the freezer.
After freezing or refrigerating, thaw in the refrigerator, bring to room temperature then beat the frosting for a few seconds so it’s creamy again.You may need to add a little milk or heavy cream if it’s too stiff.