Heat water in your double boiler. In the mixing bowl, combine the chocolate chips and ½ cup of cream, stirring as it melts until it's all smooth and mixed together.
Let the melted chocolate cool to room temperature.
In your stand mixer, add the remaining cream, the powdered sugar, and the vanilla. Beat until light and fluffy, with stiff peaks forming, for a good whipped cream.
Reserve about ⅓ of the whipped cream for topping.
Take half of the remaining whipped cream and start folding it into the chocolate. When it's somewhat incorporated, add the remaining cream and continue folding until thoroughly mixed.
Transfer your mousse into serving dishes (cups, ramekins, bowls; anything works. There should be enough for four servings, depending on your serving dish and how much you want to eat.) and put in the fridge to chill until ready to serve.
If you chill the mousse for more than half an hour, it will be pretty firm; you may want to pull it out and let it warm up for about 15 minutes before serving. The choice is yours.
Top each serving with additional whipped cream, fruit, and anything else you want to add. Enjoy!