Preheat your oven to 180c and line a tray with paper cases.
In a mixing bowl, combine the pumpkin purée, sugar and olive oil.
Stir in the milk mixture, then fold in the remaining ingredients. Divide your batter between the cases and bake for 25 minutes.
For the frosting, beat the butter with an electric whisk until pale and fluffy. Continue mixing whist adding in the icing sugar and biscoff spread.
Frost the cupcakes once cooled, then garnish with biscuits and toasted marshmallows.