In a large bowl place bittersweet chocolate pieces. Set aside while cream heats.
In a sauce pot over medium heat, bring heavy cream to a simmer. Watch it carefully, it will go from simmer, to boil all over your stove in a matter of seconds.
Pour hot cream over chocolate pieces. Use whisk to gently move around chocolate pieces so cream can evenly heat chocolate.
Allow chocolate to soften from the heat of the cream for about 3-5 minutes.
Using a whisk, stir mixture until it becomes silky and thick.
Store covered at room temperature for up to 2 days, or refrigerate for up to 1 week.