In a large bowl, heat chocolate chips and ½ c cream until the chocolate is melted and the mixture is smooth. I do this in the microwave in 20 seconds increments, stirring well between each. Set aside to cool to room temperature, stirring occasionally (this took about 15 minutes).
In the bowl of a hand mixer or stand mixer fitted with the whisk attachment, beat remaining ⅔ c chilled cream with powdered sugar and vanilla until stiff peaks form. Transfer the whipped cream to the refrigerator until the chocolate has cooled to room temperature.
Using a rubber/silicone spatula, fold the whipped cream into the melted chocolate. Once fully combined, transfer the mousse into individual serving dishes and chill for at least 2 hours. The colder it is, the more firm it will be. If you'd like it softer you can leave it at room temperature for about 15 minutes before serving.
Tags: chocolate, dessert, egg-free, makeahead, make-ahead, make ahead
https://celebratingsweets.com/chocolate-mousse/#recipe