Ensure your unsalted butter is at room temperature. Measure out all your ingredients beforehand for a smooth process.
In your mixing bowl, add the softened butter. Using a stand mixer or hand mixer, beat the butter on medium speed until it becomes creamy and pale, about 2 minutes.
Sift in the cocoa powder to prevent clumps. Mix on low speed until combined.
Slowly add the confectioners' sugar, one cup at a time. Mix on low speed to start, then increase to medium.
Add 3 tablespoons of heavy whipping cream, vanilla extract, and salt to the mixture. Beat on medium speed until fluffy. If too thick, add an extra tablespoon of cream.
If your frosting is too thick, continue to add heavy cream, one tablespoon at a time, until you reach your desired consistency. If too thin, add more confectioners' sugar.
Once your frosting is the perfect consistency, give it a final whip for about 30 seconds.
