Chocolate 'Cheese'cake

I had this with a friend at a lovely little vegan cafe in Peckham (they don't seem to have their own website, so I've linked to a review). It was absolutely amazing, so we bugged the chef to tell us what was in it. A little internet research and some adaptation later (the first likely recipe I found wasn't chocolatey enough!) and I came up with the following:

Base:
2 tbsp vegan margarine
10 digestive biscuits (McVities low-fat ones are vegan, Hobnobs are also vegan and work well)

Topping:
250 ml soya milk
1 teaspoon sugar
200g plain chocolate
1 pack Tofutti vegan cream cheese (available in most branches of Holland and Barrett)

1. Melt the margarine over a slow heat. Crush the biscuits and stir into the melted margarine. Spread over the base of a 20cm cake tin, pack well (a vegetable masher works well for this) and place in fridge to chill.

2. Melt the chocolate in a glass bowl, over a pan of hot water. Once smooth, set aside to cool for a few moments.

3. Empty the cream cheese into a large bowl and whisk until smooth. Gradually add the melted chocolate and soya milk alternately, mixing all the time. Add the sugar and mix thoroughly.

4. Pour the cheesecake mixture on top of the biscuit base, smooth with the back of a spoon and return to the fridge for at least 2-4 hours to set. You can also prepare the day before it is needed and leave to set overnight.

NB: You can easily make this recipe gluten-free by using gluten-free biscuits for the base. I made it once using Tesco Free-From Ginger Biscuits, which are both vegan and gluten free, and it worked really well.