Ingredients

1 1/2 cups confectioners' sugar 

3 tablespoons unsweetened Dutch-process cocoa powder 

Pinch of salt 

5 tablespoons unsalted butter, softened 

4 ounces cream cheese, room temperature 

7 ounces bittersweet chocolate, melted 

2/3 cup sour cream 

Preparation

Sift sugar, cocoa powder, and salt into a medium bowl; set aside.

Put butter and cream cheese into the bowl of an electric mixer fitted with the paddle attachment. Mix on medium-high until fluffy. Reduce speed to low. Gradually add sugar mixture. Mix in chocolate and sour cream. Use immediately.