Whisk together the cream cheese, pumpkin, and icing sugar until combined. Add the biscuit crumbs, spices, and melted chocolate, and mix until combined. The mixture will be thick and very sticky.
Cover tightly and refrigerate for 1 - 2 hours (or up to 24 hours) until firm.
Roll the mixture into 0.5oz balls (about 28 balls), and place on a large baking tray lined with parchment paper or a silicone mat. Freeze for 30 minutes.
For the Topping
Add the white chocolate to a microwave-safe bowl, and heat in 20 second intervals, stirring after each one, until melted and smooth. Leave to cool for 5 minutes.
Dip each truffle into the melted chocolate, and place back onto the baking tray. Sprinkle with biscuit crumbs, and allow to set completely in the fridge before serving.
Notes
Truffles can be kept in an airtight container, layered between parchment or wax paper, in the fridge for up to 1 week. They also freeze well for up to 2 months. Thaw overnight in the fridge.