Preheat oven to 180 C / Gas 4. Combine the butter, flour, light brown soft sugar and salt in a food processor. Process until mixture begins to form small lumps; press into the bottom of a 2-litre baking dish.
Bake in preheated oven until golden brown, about 20 minutes; remove from oven. Reduce oven's heat to 170 C / Gas 3.
Beat the cream cheese and 200g of caster sugar in a bowl until soft and creamy. Stir in the eggs one at a time, until smooth. Gradually stir in the soured cream, vanilla and lemon zest. Pour the mixture over the prepared base.
Bake until firm to the touch, 45 to 55 minutes. Meanwhile, make the topping by combining the blueberries, caster sugar and cornflour in a large saucepan over medium heat; cook until thickened. Allow mixture to cool.
Pour the cooled blueberry mixture over top of the cream cheese layer. Chill assembled cheesecake in refrigerator overnight.