Put the butter in a saucepan and heat gently to melt it. Put the digestive biscuits in a bag and crush them with a rolling pin. Take the pan off the heat and stir in the biscuit crumbs.
Press the crumbs into the bottom of a loose bottomed 20cm cake tin that has been greased.
Put the chocolate in a bowl in the microwave and heat gently until melted. Keep taking it out and stirring so it doesn’t cook too much.
Put the cream cheese in a bowl and whisk until soft. Add the sugar and whisk until combined. Add the vanilla and whisk again and then the eggs, one at a time, whisking after each one.
Spoon about half of the mixture into the cake tin on top of the biscuit base.
Pour the melted chocolate into the bowl with the remainder of the cheese mixture. Stir in well and then pour into the cake tin.
If you want to try and make ripples, you can use a knife to run through the mixture, swirling the two colours together. I didn’t do this as my mixture was quite runny and I was worried I would just end up with one colour rather than the ripples I wanted.
Bake in the oven at 160C for an hour until the mixture is rising around the edge of the cake but still quite soft in the middle. Turn the oven off and leave to cool in the oven.
When cooled, take out of the oven and chill in the fridge until ready to serve.
Nutritional information is approximate and a guideline only.