24 ounces bittersweet or semisweet chocolate, finely chopped
2 cups heavy cream
Put the chocolate in a large heatproof bowl. In a medium saucepan, bring the cream just to a boil over low heat. Pour the cream over the chocolate, cover and let stand for 5 minutes. Whisk the ganache gently until silky and smooth.
To make the filling, transfer 1 1/2 cups of the ganache to a medium bowl. Set the bowl over ice and whisk the ganache gently until thick and spreadable.