Preheat the oven to 325°F (160°C). Mix graham cracker crumbs, sugar, and melted butter in a bowl. Press the mixture firmly into the bottom of a 9-inch springform pan. Bake for 10 minutes, then let it cool.

In a large bowl, beat the cream cheese and sugar until smooth and fluffy. Add eggs one at a time, mixing after each addition. Stir in vanilla extract and sour cream until well combined. Pour the mixture over the cooled crust.

Place the pan on a baking sheet and bake for 50–55 minutes, or until the center is just set. Turn off the oven and leave the cheesecake inside for 1 hour with the door slightly open. Remove and let cool to room temperature, then refrigerate for at least 3 hours.

In a saucepan, combine blueberries, sugar, and lemon juice. Cook over medium heat until the berries start to release their juices. Stir in the cornstarch mixture and cook for 2–3 minutes until thickened. Cool the topping completely before spreading it over the chilled cheesecake.