Crush the biscuits well: place them in a plastic bag and firmly roll over the bag with a rolling pin several times until the biscuits are finely and evenly crushed. Mix all the crust ingredients until moist clumps form. Press mixture onto bottom of a lined springform pan. Cook at 160C until crust is golden, about 20 minutes.

Stir white chocolate in top of double boiler set over simmering water until chocolate melts. You can also do it in the microwave but DO NOT OVERCOOK or the chocolate will never be smooth again. Cool to lukewarm, stirring occasionally. Don't let it cool too much or you'll have hard lumps of chocolate throughout the cheesecake, as we discovered last time we made it.

Using an electric mixer, beat cream cheese and sugar in a large bowl until smooth. Gradually beat in sour cream and juice, then melted chocolate, peel, vanilla and cinnamon. Beat in eggs one at a time.

Spoon filling into crust. Bake at 160C until edges of cheesecake puff and crack and centre is just set, about 1 1/4 hours. Remove from oven and cool.

Refrigerate overnight before serving. Don't think you can make it in the afternoon and refrigerate for a couple of hours before serving! It will still be squishy, if not warm, inside, and won't taste too flash.