Place chocolate chips in a large bowl, or in the bowl of a stand mixer. Pour the cream into a saucepan, and bring to a boil. As soon as the cream boils up to the top of the pan, quickly remove it from the heat, and pour it over the chips. Let stand for a minute or two, then stir with a whisk, or use the paddle attachment for the mixer, to mix until smooth. Be sure to scrape the bottom of the bowl occasionally. Stir in the vanilla until well blended. Place a piece of plastic wrap directly on the surface, and allow to cool at room temperature, or in the refrigerator.