Lightly grease a 20 cm (8 inch) nonstick, loose-based round cake tin.
Melt the butter in a saucepan, stir in the biscuit crumbs, then press them over the base and side of the cake tin. Bake in a preheated oven, 150°C (300°F), Gas Mark 2, for 10 minutes.
Beat together the remaining ingredients in a bowl, spoon the mixture into the cake tin and bake for 40 minutes until just firm. Turn off the oven and leave the cheesecake to cool in the oven for an hour.
Transfer the cheesecake to the refrigerator for 2 hours, then serve decorated with juliennes of orange and lemon rind.