1½ cups finely crushed plain chocolate biscuits
80g butter, melted
½ tsp ground cinnamon
3 packets 250g cream cheese, softened
250g sour cream
1 cup caster sugar
250g dark cooking chocolate, melted and cooled
½ cup Irish cream liqueur
2 Tbsp thickened cream or milk
2 tsp vanilla
Preheat oven to 180°C. Combine the crushed biscuits, butter and cinnamon in a medium bowl, tossing gently to mix. Press the mixture onto base and up sides of a 25cm springform tin. Set aside.
Combine cream cheese, sour cream, sugar and chocolate in the large bowl of an electric mixer. Beat on medium to high speed for 4-5 minutes until smooth. Using a wooden spoon, stir in eggs until just combined. Stir in liqueur, cream and vanilla.
Pour filling into crust-lined tin and put in another shallow baking tin in case of leaking. Bake for 50-60 minutes or until centre appears nearly set when gently shaken. Cool in tin on a wire rack for 15 minutes.
Loosen crust from side of tin using a small, thin knife. Cool for 30 minutes more. Remove side of tin. Cool for 1 hour. Cover and chill for at least 6 hours or up to 24 hours.