In a small microwave safe bowl, add the chocolate chips and 1/3 cup of heavy cream.
Microwave for 45 seconds, remove from the microwave and stir until melted and shiny. If needed, microwave for an extra 15 seconds. Set aside 10 minutes to cool down at room temperature. You can also melt the chocolate chips and heavy cream in a non-stick saucepan over medium heat constantly stirring until fully melted.
In a stand mixer, add the remaining 1 cup of cold heavy cream and beat on high speed using the whisk attachment. Whisk until a soft stiff peak forms - don't over-beat the cream, or it becomes too dense, and the mousse won't be fluffy.
Gradually pour the melted chocolate mixture into the whipped cream and stir at the same time to gently incorporate. The mixture should be light, fluffy, the color depends on the percentage of cocoa your chocolate chips contain. Mine are 80% cocoa so the color is quite dark.
Optional - for a former mousse, sift in 2 tablespoons of unsweetened cocoa powder in the mousse, stir well to incorporate.
Transfer the mousse into ramekins, cover the top of the ramekins with plastic film wrap and refrigerate overnight to set.
Serve the next day with extra whipped cream on top, shredded dark chocolate, and strawberries.