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

In the food processor, blend the digestive crackers and granulated sugar until fine crumbs form. Melt your butter and combine it with the crust mixture.

Press the mixture into the base of the springform pan, ensuring it's evenly packed. Bake for 10 minutes, then allow to cool.

In a mixing bowl, stir together the fresh blueberries, sugar, flour, and lemon juice. Allow to sit for about 10 minutes.

In a separate bowl, mix the all-purpose flour and dark brown sugar for the crumble topping. Combine with melted butter until it resembles coarse crumbs.

In a large mixing bowl, beat the cream cheese and sugar until smooth. Add sour cream, cornstarch, and vanilla extract.

Add the eggs one at a time, mixing just until combined after each addition. Pour the filling into the baked crust.

Spoon the blueberry mixture over the cheesecake filling and sprinkle the crumble topping over the blueberries.

Prepare a water bath by placing the springform pan in a larger dish filled with hot water. Bake for 1 hour and 20-30 minutes.

Once baked, turn off the oven and leave the cheesecake inside for about 1 hour.

After cooling, cover with plastic wrap and refrigerate for at least 6 hours or overnight before serving.