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

Pulse the digestive or graham crackers with sugar until a fine crumb forms. Melt the butter and combine it with the crumb mixture, then press into the prepared pan.

Bake the crust for about 10 minutes, then let it cool completely.

Toss the fresh blueberries with sugar, flour, and lemon juice in a mixing bowl, then set aside.

Mix flour and dark brown sugar for the crumble topping, drizzle in melted butter, and stir until crumbly.

Beat the softened cream cheese on medium speed until creamy, then gradually add sugar and blend until smooth. Mix in sour cream and cornstarch, followed by vanilla extract.

Add the large eggs two at a time, mixing on low speed until just combined after each addition.

Pour the cheesecake batter over the cooled crust, sprinkle the blueberry filling over the top, and add an even layer of crumble topping.

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

Turn off the oven and leave the cheesecake inside with the door slightly ajar for about one hour. Then refrigerate for at least 6 hours, or overnight, before serving.