Makes 2 3/4 cups (enough to frost an 8- or 9-inch layer cake or 24 cupcakes)
(24 ounces) semisweet chocolate, chopped
unsalted butter (3 sticks), at room temperature
- Melt the chocolate in a medium bowl set over (but not in) a saucepan of simmering water, stirring often, until melted. Let cool to room temperature (do not let it solidify).
- Using an electric mixer, beat the butter until creamy. With the mixer running, slowly add the chocolate and beat until combined and smooth.