Bloom the gelatin: Sprinkle the gelatin powder into 30 ml of ice-cold water*. Mix the water instantly and let it set in the fridge for at least 10 minutes.
Add the milk, heavy cream, and Vimto syrup in a saucepan and bring it to a boil. While it boils, place the chocolate in a heat-proof bowl.
Pour the hot milk over the chocolate chips and let it sit until the chocolate is melted. Then combine them using a hand whisk until the chocolate is completely incorporated into the milk.
While the chocolate mix is hot, add the bloomed gelatin and whisk it until it’s melted and combined into the mixture. Make sure the mixture is still hot when you add in the gelatin, or it will not incorporate properly. Set it aside and let it cool to room temperature.
Once the chocolate mix has cooled to room temperature, pour it into the whipped cream while gently folding it in. Make sure to do this process slowly to retain the airiness of the whipped cream. You want the mousse to be as light and airy as possible. Keep folding until no streaks of chocolate are left and everything is well incorporated.
Assemble the mousse: In your dish of choice, pour a layer of the Vimto caramel, then set it in the fridge for 5 mins. Top it with the mousse and add another layer of caramel. Let the mousse set in the fridge for at least 2 hours before serving.