Ingredients
Method
1.Preheat oven to moderate, 180°C. Grease a 23cm round springform pan and line base and side with baking paper.
2.In a food processor, crush biscuits to fine crumbs. Add butter; pulse to combine.
3.Spread crumb mixture evenly over pan base, pressing firmly with a fork or base of a glass. Bake 10 minutes on middle rack; cool.
4.Increase oven to hot, 200°C.
5.In a large bowl, using an electric mixer, beat cream cheese, sugar, flour and vanilla together until smooth. Add eggs and yolk, one at a time, beating well after each addition.
6.Beat sour cream, zest and half juice into mixture. Pour over base. Bake 10 minutes.
7.Reduce oven to very slow, 120°C. Bake a further 20-25 minutes – the centre will wobble slightly. Cool in turned-off oven, with door ajar, 2 hours.
8.In a bowl, whisk extra sour cream, extra sugar and remaining juice together.
9.Spread sour cream mixture over cooled cheesecake. Chill 4 hours or overnight.
10.Serve in wedges with extra cream, if liked.