In a medium sized heavy-based saucepan, place the marshmallows, butter, chocolate and water. Over low heat, gently melt all ingredients together stirring every now and then. Once all are melted remove from heat and let cool slightly.
Meanwhile to make the raspberry sauce, place raspberries and sugar into a small saucepan and slowly heat to a simmer. Let cook for 5 minutes until raspberries have defrosted and the sugar has dissolved, stirring occasionally. If the sauce is too thin, add some cornflour, and let boil for a little longer until it thickens slightly.
Meanwhile, whip the cream until thick and add the vanilla extract. Fold into the cooled chocolate mixture until well combined.
Carefully divide the raspberry sauce evenly over the 4-6 glasses and pour the chocolate mousse over the top. Chill until ready to serve. Top with any excess cream, fresh berries and coconut chips. Again, this can be made ahead of time if need be.
Recipe and Photography by Adeline & Lumiere