Preheat the oven to 180c and line a baking sheet with baking paper.
Start by making your chocolate mousse. Combine all ingredients in a saucepan, and whisk together over a medium heat. Continue to whisk as the mix slowly heats up and thickens. This process can take 10-15 minutes. Ensure you whisk to prevent it from burning to the bottom and curdling the mixture. Do not increase the heat too much as again, this will curdle the mixture.
The mixture is done once you dip a spoon into it, then run your finger through the back of the spoon and the line holds its place. Pour into a glass bowl and cover with gladwrap, pushing the glad wrap down on the surface of the mousse to prevent a skin. Leave in the fridge to cool entirely – about 2-4 hours.
Meanwhile, as the mousse cools, make your graham cracker biscuit. Mix all the ingredients together until well combined and a dough forms.
Press out into one large biscuit on the baking sheet, ensuring a lot of it crumbles around the edges. This will create your biscuit crumbs as well as some bigger pieces. Place in the oven to cook for around 6-8 minutes until golden.
Remove from the oven and allow to cool.
Once you’re ready to serve your mousse, portion out into glasses and chill whilst you make the marshmallow fluff.
In a separate bowl, or bowl of your stand mixer, mix together your gelatin and 2 tbsp of your water. Set aside.
In a small pot, mix together your maple syrup, vanilla and remaining water. Heat, whilst stirring, until it comes to a rolling boil.
Now, with your stand mixer or electric beater turned on high, add your maple mix to the gelatin gradually.
Continue to beat for between 8-10 minutes, until your mix starts to thicken and is just before reaching soft peaks.
You will then want to work quickly to portion across your mousse. The marshmallow fluff starts to set pretty quickly as it cools down. Top your mousse with fluff, followed by a few biscuit crumbs and serve!