Preheat your oven to 350°F (175°C). In a food processor, blend together the digestive or graham crackers, granulated sugar, and melted butter until they resemble wet sand. Press this mixture firmly into the bottom of a lined springform pan. Bake for 10 minutes until lightly golden, then set aside to cool.

In a medium bowl, gently toss the fresh blueberries with flour and lemon juice, ensuring each berry is coated to brighten their flavor. Then, prepare the crumble by mixing dark brown sugar and all-purpose flour in another bowl. Add melted butter until the mixture forms clumps and resembles coarse crumbs.

In a stand mixer, beat the room temperature cream cheese until smooth, about 2-3 minutes. Gradually mix in the granulated sugar until creamy. Then, add in the sour cream and cornstarch, mixing until fully combined. Incorporate the eggs one at a time, ensuring each is well blended before adding the next, achieving a luscious Blueberry Crumble Cheesecake filling.

Pour the cheesecake batter over the cooled crust, smoothing the top with a spatula. Scatter the lemony blueberries evenly over the batter, followed by the crumble mixture. Place the cheesecake in the oven and bake for 1 hour and 20-30 minutes, until slightly wobbly in the center and the edges are set.

Turn off the oven and let the cheesecake cool inside for 1 hour, allowing it to stabilize without sudden temperature changes. Afterward, transfer it to the fridge and refrigerate for at least 6 hours—or preferably overnight—to ensure it firms up beautifully for a perfect slice of Blueberry Crumble Cheesecake.