Preheat your oven to 160ºC (325ºF) and line the bottom of a 23 cm (9-inch) springform pan with parchment paper.

Combine crushed digestive or graham crackers with granulated sugar and melted butter. Press the mixture into the bottom of the pan and bake for about 10 minutes.

Toss the fresh blueberries with all-purpose flour, sugar, and lemon juice in a bowl and set aside.

In a separate bowl, mix all-purpose flour with brown sugar and melted butter until crumbly for the topping.

Beat the cream cheese with granulated sugar until smooth. Gradually mix in sour cream, cornstarch, and vanilla extract, then add eggs one by one.

Pour the cheesecake filling into the cooled crust, layer with blueberry mixture, and sprinkle crumble topping.

Place the springform pan in a larger baking dish filled with hot water, and bake for 80-90 minutes.

Cool in the oven for 1 hour, then refrigerate for at least 6 hours before serving.