Heat the cream in a small saucepan over medium heat until it simmers. Pour over the chocolate and let stand for 2 minutes, then gently stir with a rubber spatula until the chocolate is completely melted and smooth.
If Using for Truffles: Refrigerate for at least 8 hours, or overnight, until thoroughly chilled. Then, scoop into balls and roll in cocoa powder or chopped nuts.
If Using for a Glaze: After mixing, slowly pour the ganache over the cake or cupcakes, allowing it to drip over the sides.
If Using for a Frosting: Refrigerate for at least 1 hour, then use an offset spatula to spread. Alternatively, you can also whip the chilled ganache for a lighter frosting.