Put the mascarpone cream cheese, icing sugar, and vanilla extract into an electric mixer - I use my KitchenAid with the whisk attachment and whisk until smooth and combined.
Add in the marshmallow fluff and whisk again - at first it will look lumpy but if you stick with it it'll go nice and smooth.
Add in the liquid double cream and whisk until stiff. Make sure to scrape down the edges of the bowl and continue to whisk until very thick and it holds itself when you lift the whisk out!
Dollop on top of the biscuit base andsmooth over - refrigerate for 6+ hours, or preferably overnight (12+ hours) so it has time to set properly!
Decorate your s'mores cheesecake by toasting some mini marshmallows with a blowtorch so they all mould together nicely.
Crush some more biscuits and sprinkle them all over & drizzle on some melted chocolate or chocolate curls on top!
ENJOY!
Notes
If it looks like your cheesecake isn't setting, or its a but sloppy, or you're even not sure.. try it anyway. Try to set the mix anyway! If it still doesn't set, freeze it and have an ice cream cheesecake!
If you think its not going to set it might be because you haven't whipped it enough, or the fridge isn't cold enough - mine is at 2C as I like my stuff super cold! If you think the mix is just a lumpy icky mess then stick with the whisking! There is such a thing as over-whisking though so don't choose the supercharged high speed - stick at a medium-high speed when mixing!
This cheesecake will last in the fridge, covered, for 3 days!
You can find the marshmallow fluff with the Nutella and such in the supermarket!