Step 1: Prepare the Crust

1. Preheat oven to 160°C (325°F). Line the bottom of a 23 cm (9-inch) springform pan with parchment paper.

2. In a food processor, blend biscuits and sugar until finely crushed. Add melted butter and process again to combine.

3. Press the crumb mixture into the base and sides of the prepared pan using the bottom of a glass.

4. Bake for 10 minutes. Let it cool completely. Keep the oven on.

Step 2: Prepare the Blueberry Layer

1. In a small bowl, combine blueberries, sugar, flour, and lemon juice. Toss until no dry flour remains. Set aside.

Step 3: Make the Crumble Topping

1. In another bowl, mix flour and brown sugar.

2. Add melted butter and stir with a fork until large crumbs form. Set aside.

Step 4: Make the Cheesecake Filling

1. In a stand mixer fitted with paddle attachment, cream cream cheese on low speed for 1 minute.

2. Add sugar gradually and beat until smooth, scraping the sides as needed.

3. In a separate bowl, combine sour cream, cornstarch, and vanilla. Add to cream cheese mixture and mix until combined.

4. Add eggs, two at a time, beating on low speed after each addition until incorporated. Scrape sides and stir one final time.

Step 5: Assemble and Bake

1. Pour the cheesecake batter into the cooled crust.

2. Evenly distribute the blueberry mixture on top, followed by the crumble topping.

3. Place the springform pan into a larger baking dish for a water bath. Pour hot water halfway up the sides.

4. Bake for 1 hour 20–30 minutes. Gently shake the pan; the center should still jiggle slightly.

5. Turn off the oven, crack the door, and let the cheesecake cool inside for 1 hour.

6. Remove from oven and cool completely at room temperature. Refrigerate for at least 6 hours, preferably overnight.