Start by placing the unsalted and salted butter in a large mixing bowl. Make sure your butter is at room temperature, as this will help it blend smoothly.
Using your electric mixer, beat the butter on medium speed until it is creamy and light in color, about 2-3 minutes.
Gradually add in the cocoa powder and powdered sugar, one cup at a time. Mix on low speed to avoid a sugar cloud, then increase to medium speed until fully combined.
Pour in the vanilla extract, and continue mixing to combine.
Add the heavy cream, starting with 3 tablespoons. Mix well, and if the frosting is too thick, add an additional tablespoon of cream until you reach your desired consistency.
Give your frosting a taste. If you’d like it sweeter, feel free to add a bit more powdered sugar or cocoa powder as needed.
