In a mixing bowl, add the room temperature salted butter. Using your electric mixer, beat it on medium speed until it’s light and fluffy, about 2-3 minutes.
Gradually add the dry brownie mix to the creamed butter. Beat the mixture on low speed to avoid a cloud of cocoa powder, then increase the speed to medium and mix until well combined.
Sift the powdered sugar into the bowl to prevent lumps. Beat it into the brownie mixture on low speed until fully combined.
Pour in the heavy cream and mix on medium speed until the frosting reaches your desired consistency.
Taste your frosting and adjust sweetness or richness as desired by adding more powdered sugar or a pinch of salt.
