This will make 2 cups. Feel free to double/half it as necessary.
4 tbsp. unsalted butter (cut into 4 pieces)
1 ounce unsweetened chocolate, chopped
1/4 tsp. salt
1/4 tsp. instant coffee crystals
3/4 cup cocoa powder
3 cups confectioners' sugar
1 cup skim milk
1. Melt butter and chocolate together until smooth. Stir in salt and coffee crystals until dissolved. Transfer to medium bowl and cool 10 minutes.
2. Whisk cocoa and sugar in a medium bowl. Using an electric mixer, gradually add cocoa mixture to melted chocolate mixture (use low speed). Gradually add milk, beating until milk is completely incorporated. Increase speed to medium-high and beat until light and creamy, about 1 minute.