Preheat the oven to 350°F (175°C). In a medium bowl, combine the graham cracker crumbs, sugar, and melted butter. Press the mixture firmly into the bottom of a 9-inch springform pan. Bake for 8-10 minutes, then let cool.
In a large bowl, beat the cream cheese and sugar until smooth. Add in the vanilla extract, lemon juice, and cornstarch, mixing well.
Add eggs one at a time, beating after each addition just until combined. Pour the filling over the prepared crust.
Place the springform pan in a water bath and bake for 50-60 minutes until the center is almost set. Turn off the oven, crack the door, and let the cheesecake cool gradually for 1 hour.
In a small saucepan, combine the blueberries, sugar, and lemon juice. Cook over medium heat until the blueberries start releasing juice, about 5 minutes.
Stir in the cornstarch mixture and cook until the sauce thickens, around 2-3 minutes. Let cool completely.
Spread the blueberry topping evenly over the chilled cheesecake before serving.
Notes
Ensure all ingredients are at room temperature for a smoother filling. Avoid over-mixing to prevent cracks in the cheesecake.