Combine water, syrup and sugar in a saucepan, bring to the boil until soft ball stage, or 235 degrees on a candy thermometer. Sprinkle the gelatin over the cold water and let dissolve. Remove the syrup from the heat, add the gelatin and mix. Whip the whites until soft peaks form and pour the syrup into the whites. Add the vanilla and continue whipping until stiff. Transfer to a piping bag. If you don’t want to make marshmallow you can use brought marshmallow. Heat in a pre-heated oven 180 c, allow marshmallow to slump slightly. It will expand and brown a little. Let cool and proceed with the chocolate dipping.
If you have a silicone dome mould you can melt dark chocolate then line the mould with chocolate and allow the chocolate to set. Pipe some marshmallow into the chocolate, about two thirds up. Lightly put some raspberry jam onto top of biscuit and then put it jam side down into the marshmallow. Push biscuit down to allow room for the chocolate. Smooth out and allow to set. When set take out chocolate domes out of moulds. If not mould you can just put marshmallow onto top of biscuit and then dip in the chocolate and wait for it to set.