Put marshmallow and butter in a pot.
Melt while stirring in a medium heat.
After all the marshmallows melted, turn off the heat.
Pour rice crispies into a pot then stir it until all the ingredients mix well.
After that quickly place the rice crispies mix into a large short tray then shape to thin using a spatula. Set aside.
Boil water in a pot, then in a bain-marie melt the dark chocolate chips.
After the chocolate melted, spread it on top of the rice crispies mix.
Gently roll the rice crispy chocolate like making sushi then cut into pieces.
Rice crispy chocolate rolls are ready to serve.