Instructions

• Place ½ cup (113 g) unsalted butter and 1 ounce (28 g) unsweetened chocolate in a small saucepan and melt over low heat, stirring constantly until smooth. (Or microwave in short bursts, stirring between, until melted.) Remove from heat and let cool until lukewarm and still pourable.
• In a large mixing bowl combine 16 ounces (454 g) powdered sugar, ½ teaspoon (2 g) pure vanilla extract, ¼ cup (57 g) milk, and ¼ teaspoon kosher salt. Using a hand mixer or stand mixer on medium-low speed, beat until the sugar is mostly incorporated and the mixture is smooth.
• With the mixer on low speed, slowly add the cooled melted butter and chocolate to the powdered sugar mixture. Continue beating on low until fully incorporated and smooth, scraping down the bowl as needed.
• If the frosting is too thick to spread, add additional milk 1 teaspoon at a time, beating briefly after each addition, until you reach the desired consistency.
• Cover the bowl and set the frosting aside at room temperature until it thickens to a spreadable consistency.
• Use a knife or piping bag to frost cakes or cupcakes.