Chocolate Frosting for Chocolate-Raspberry Cake

Sift together sugar, cocoa, and salt. Beat cream cheese with butter on medium-high speed until smooth. Reduce speed to medium-low; gradually add cocoa mixture and beat until combined. Pour in chocolate in a slow, steady stream. Add creme fraiche; beat until combined. Frosting can be stored in refrigerator up to 5 days; bring to room temperature and beat before using.