Peanut-Butter Cheesecake

This is my version of Nigella's peanut butter cheesecake and it is phenomenal. You have to try it - It is sure to impress your guests. 

Ingredients:

Base:

200 grams/7oz of digestive biscuits (if you can't get any use graham crackers)

85g/3oz ounces unsalted butter (softened)

Filling:

500g/1lb of cream cheese

3 eggs

3 egg yolks

200 g/7oz caster sugar (or superfine sugar in US)

125ml/4.24 fl oz of sour cream

250 g/9oz of smooth peanut butter

Topping:

250 ml/9fl oz sour cream

100g/3.5 oz milk chocolate chips

30g/1.25 oz soft brown sugar

How to:

1.  Preheat the oven to 170C/325F/Gas 3 (remember if using a fan lower heat about 20 C)
2. Make the base: process the biscuits (or crushed graham crackers) and butter in a food processor. Once the mixture comes together in a clump, turn it out into a 23cm/9in springform tin and press it into the bottom of the tin and up the sides, using your fingers.  Place in the fridge for at least 10 minutes or until your filling is ready. I do not own a food processor so I crushed the biscuits in a bag first and then slowly kneaded the butter in using my fingers. I also HIGHLY RECOMMEND buying a springform tin as opposed to using a traditional 9 inch tin. Here is a description of what a springform is - http://whatscookingamerica.net/Q-A/SpringForm.htm. I actually had no clue until I started baking about a year ago.
3. For the filling, combine the cream cheese, eggs, egg yolks, sugar, sour cream and peanut butter in a food processor until smooth. I used a blender & it came out fine.
4. Pour and scrape the filling mixture into the cheesecake base in the chilled springform tin and cook for 1 hour, checking after 50 minutes. The top – only – should feel set and dry. When cooked, remove from the oven.
5. Make the topping:  warm the sour cream and chocolate chips with the brown sugar gently in a small saucepan over a low heat until melted & combined.
6. Spread the topping very gently over the top of the cheesecake (IN THE SPRINGFORM TIN). Put it back in the oven for 10 minutes.
7. Once out of the oven, let the cheesecake cool completely in its tin, then cover and put into the fridge overnight.
8. Remove the cheesecake from the fridge about 15 minutes before serving so that it is easier to spring from the tin. It gets mushy - so keep it cool.