Someone reminded me of this tonight, it's been a long long time since I made it … and said she'd found it on the net, I'd forgotten that I'd contributed it to The Umrats Online Cookbook years ago (there's more of the cookbook here: http://www.clothandclay.co.uk/umra/cookbook/contents.htm )
You'll need a large, 9 or 10 inch cake tin with a removable bottom: the spring-loaded sided ones are best. This recipe takes at least two days. If you need to, you can double the ingredients, but allow for longer cooking time with the cheesecake bit. As it stands, it'll do eight to twelve slices, each about the calorific value of a box of Belgian truffles.
First make a biscuit base. Take half a pack of chocolate-coated digestive biscuits, or the crumbly oaty ones (Hobnobs), and crush into crumbs (or whizz in a processor). Mix with 4 oz melted butter, and press the whole lot firmly into the bottom of the pan.
The next layer is a cooked cheesecake. Heat the oven to gas mark 4. In a big bowl, beat 12 oz of cream cheese until it's smooth and light. Add 6 oz caster sugar. Beat together 2 eggs, and add to the bowl, mixing really well. You can add a tablespoon of your favourite booze here if you like, or a tablespoon of strong coffee. Pour this over the base, and bake in the oven for about half an hour, until it is set and doesn't wobble a lot in the middle. Take it out of the oven, and leave it to cool for not more than ten minutes, while you grate or finely chop a normal-sized bar of plain chocolate. Spread the top of the warm cheesecake with a small tub of creme fraiche or sour cream. Sprinkle the chocolate on the top. As the cream gets hot it will melt the chocolate, then as it cools it all sets. You are now on layer four. This is a good point to get to the day before, if you have a lot of time on the day or you're skipping layers five and six.
Layers five and six are optional, but are both made the same way. Layer five is made with white chocolate, layer six with the best dark chocolate you can find.
When the cake is cold: Take one large bar of chocolate, or two normal sized ones. Melt slowly, in a bowl over hot water or at a very low temperature in the microwave, stirring as you go.
Whip a half-pint (10 fl oz) of double cream until it is quite firm. Take a spoonful and stir it into the melted chocolate, to thin it down a bit, then add the chocolate to the cream. Stir fast, it starts to set almost straight away. You can add some more liqueur here if you like. Spoon the mixture onto the cake, spread it out and leave it to cool and set.
Layer seven is the final layer, and you can leave this until the last minute if you want. It's easier if you get the cake out of the tin and put it on a plate. You don't need to get it off the bottom of the tin, just release the sides. Whip as much double cream as you want, at least 10 fl oz, until it is stiff. Pile it on top of the cake, and sprinkle with chopped dark chocolate, or those fancy chocolate cutouts you can buy. If you want to add fresh fruit (like strawberries) this is the place and time.
Cut in thin wedges; and this is me telling you, they need to be thin.