- 1/2 cup (1 stick) unsalted butter
- 1/4 cup unsweetened cocoa powder
- 6 tablespoons buttermilk
- 1 pound confectioners' sugar
- 1 teaspoon vanilla extract
- Combine the butter, cocoa powder, and buttermilk in a medium saucepan and heat until the butter melts and the mixture just comes to a boil. Remove from the heat and whisk until smooth. Sift the confectioners' sugar into a medium mixing bowl. Add the chocolate mixture and vanilla extract to the powdered sugar and whisk until smooth.