To make the base: Crush biscuits in a blender, add melted butter, process briefly then press into springform or loose-bottom tin. Chill.
To make the filling: Beat cream cheese and sugar together; beat in pumpkin, cinnamon, nutmeg, and salt. Continue beating and add eggs one at a time. Pour onto the set base. Bake at 180°C for 50 minutes.
To make the topping: Beat sour cream, sugar, and vanilla together. Pour over cheesecake and bake for a further 5 minutes.
