Step 1: Prepare the Pan

1. Preheat oven to 160°C (320°F) or 140°C (275°F) for fan ovens.
2. Line the base of an 8-inch (20cm) springform pan with parchment paper.
3. Butter the sides and line them with parchment for easy removal.

Step 2: Make the Biscuit Crust

1. Crush the crackers into fine crumbs using a food processor or a ziplock bag with a rolling pin.
2. Mix in melted butter until the mixture resembles wet sand.
3. Press the crumbs firmly into the base of the pan, spreading slightly up the sides.
4. Chill in the fridge while preparing the filling.

Step 3: Prepare the Cheesecake Filling

1. Beat cream cheese in a mixing bowl until smooth (20 seconds max).
2. Add flour, sugar, vanilla, and sour cream, mixing until just combined.
3. Add eggs one at a time, mixing briefly after each.
4. Gently fold in blueberries and pour the batter over the crust.

Step 4: Bake & Cool

1. Bake for 70 minutes—the center should be slightly jiggly.
2. Turn off the oven, crack the door open, and let the cheesecake cool inside for 2 hours.
3. Refrigerate for at least 4 hours or overnight for best texture.

Step 5: Make the Blueberry Topping

1. In a saucepan, simmer 1 cup blueberries, sugar, lemon juice, and vanilla for 7 minutes.
2. Mix cornstarch with water and stir it into the sauce to thicken.
3. Remove from heat and stir in the remaining fresh blueberries.
4. Let cool completely, then spread over the chilled cheesecake.