In a bowl, mix together digestive biscuit crumbs and melted butter. Evenly divide the crumbs between 5 serving glasses or dishes. Chill in fridge whilst you prepare cheesecake filling.
Place marshmallow is a big microwave safe bowl and microwave for up to 60 second bursts until marshmallows puff up and begin to melt. Stir the marshmallows using a buttered spatula until smooth.
Beat together cream cheese and sugar in a bowl until smooth. Stir in melted marshmallow and beat until mixed, for about a minute
Whip cream in bowl of stand mixer until stiff peaks form and then gently fold into cheese mixture.
Pour or pipe filling onto the crusts. Cover and chill in the fridge for up to four hours or overnight.