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 full 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 still too stiff.