Chestnut chocolate truffle torte

This is my adaptation of a fantastic Delia Smith recipe which I've done several times before - this time though, I've added some chestnut  purée to make it more Christmassy!  It's the ultimate decadent chocolate dessert, so I'm rounding off Christmas dinner with it (accompanied by my summer fruit terrine and a spiced Christmas panna cotta).

Ingredients

100g Amaretti biscuits

400g dark chocolate, broken

5 tbsp liquid glucose

3 tbsp dark rum

2 tbsp Amaretto

200g chestnut purée

570ml double cream

Cocoa powder for dusting

Method

1. Line the base and sides of a 23 cm cake tin, and grease with walnut oil. 
2. Set aside 3 or 4 of the biscuits and crush the rest into powder. 
3. Sprinkle the biscuit crumbs over the base of the tin and place in the fridge.
4. Place the chocolate, alcohol, glucose and chestnut purée in a bowl over a pan of barely simmering water, leaving until melted and smooth.  Remove from the heat and allow to cool for 5 mins.
5. In a separate bowl, beat the cream until slightly thickened.
6. Fold half the cream into the chocolate mixture with a metal spoon.  Then fold that mixture into the rest of the cream.
7. Spoon into the prepared tin, gently tapping the sides of the tin to even the mixture out.  Cover with clingfilm and refridgerate overnight.
8. Before serving, run a palette knife round the edge and shake it to turn out on to a cake stand.  
9. Dust with sifted cocoa powder and the sprinkle the remaining Amaretti biscuits in the centre.