In a food processor, process the biscuits and butter until they form a fine crumb then press into the base of a greased and lined 20cm (8") round, springform tin so that it comes up the sides.

Cover and refrigerate for 1 hour.

Pre-heat the oven to 150C (330F) fan-forced.

To make the filling, melt the chocolate in the microwave and when smooth, set aside.

In the bowl of an electric mixer, beat the eggs until thick and fluffy.

Gradually add the sugar and mix until pale.

In a separate bowl, beat the cream cheese and cream together until smooth and thickened then fold the melted chocolate in until smooth.

Fold the egg/sugar mixture into the chocolate cream then add the rum and vanilla.

Sift the flour, salt and bicarb together and fold them through the batter.

Spread the mixture into the chilled base.

Bake for 50-60 minutes.

Leave in the tin to cool then cover and refrigerate until firm.

Served topped with extra whipped cream and chocolate.