Grease a 20cm (8 inch) round spring form cake tin and line the base with foil.
Grind the biscuits in a food processor to a fine crumb and add the melted butter and mixed spice and mix well. You should have a mixture like wet sand.
Using clean hands, press the biscuit mixture into the base and up the sides of the cake tin. Place in the refrigerator for 15 – 20 minutes, until firm.
Pre-heat oven to a moderate 180c (350f).
In a medium sized bowl, beat the cream cheese with an electric mixer until smooth, add the vanilla, sugar, lemon juice and rind and mix well. Add the eggs, one a time, beating after each addition, until smooth.
Pour into chilled base and bake for 45 minutes or until the middle is just firm to touch. Remove from the oven and pour the topping over (see below) return to the oven for another 7 – 8 minutes. Cool and then refrigerate until chilled and set. Allow at least 3 hours.
For the topping: Combine the sour cream, vanilla, lemon juice and caster sugar in a small bowl, mix well and pour over hot cheesecake.
When set, decorate with whipped cream and berries, if desired.