bittersweet chocolate frosting

MAKES ABOUT 4 ½ CUPS

• 10 ounces bittersweet chocolate (60 to 65 percent cocoa is ideal)
• 1 ½ cups heavy cream
• 1 ½ sticks (6 ounces) unsalted butter, at room temperature

1. Melt the chocolate with the cream in a double boiler or a metal bowl set over a pan of simmering water. Whisk to blend well. Remove from the heat and let stand, whisking occasionally, until the chocolate cream sets up, or thickens, to the consistency of mayonnaise.
2. Place the butter in a large mixer bowl and with an electric mixer on medium speed, whip the butter until light and fluffy. Add the chocolate cream and whip until lighter in color and somewhat stiff, about 3 minutes. Do not whip too long, or the frosting may begin to separate.