Preheat the oven to 180 degrees C. For the base, put biscuits in a plastic bag, seal and roll with a rolling pin, ensure that they are all evenly crushed. In a bowl, add in the icing sugar and ground ginger, mix together.
Melt the butter in a pan, add to the biscuit mix, stir.
Press the biscuit mixture into the base of a 23cm springform cake tin. Bake in the oven at 180 degrees C for 10 minutes. Remove from oven and increase oven temp to 230 degrees C.
Combine the cream cheese, caster sugar, lemon zest and flour in a large bowl. Beat at a medium speed until well blended and smooth. Add in the eggs, one at a time, mixing well after each addition. Pour the filling over the biscuit base.
Bake in the oven at 230 degrees C for 10 minutes, then reduce to 120 C and continue baking for 50 minutes.
Meanwhile make the topping. Combine sour cream, grated ginger and caster sugar together. Pour on top of the cake and continue baking for a further 20 minutes.
With a knife, loosen cake from sides of tin. Allow to cool slightly, then push up base of the tin to remove cheesecake. Before serving, grate some lemon and sprinkle on top.