Step 1: Prepare the Crust

1. Preheat your oven to 350°F (175°C).
2. In a medium bowl, combine graham cracker crumbs, melted butter, and sugar. Mix until the texture resembles wet sand.
3. Press the mixture firmly into the bottom of a 9-inch springform pan, ensuring even coverage.
4. Bake for 10 minutes, or until lightly golden brown. Set aside to cool.

Step 2: Make the Cream Cheese Filling

1. In a large bowl, beat the softened cream cheese until smooth and creamy, using an electric mixer.
2. Gradually add the powdered sugar, and continue mixing until fully incorporated.
3. Mix in the vanilla extract, lemon juice, and cornstarch until smooth.
4. Add the eggs, one at a time, beating on low speed just until combined. Do not overmix.
5. Pour the cream cheese mixture over the cooled crust, spreading it evenly.

Step 3: Bake the Cheesecake

1. Lower the oven temperature to 325°F (160°C).
2. Bake the cheesecake for 40-45 minutes, or until the edges are set and the center is slightly jiggly.
3. Turn off the oven, crack the door open slightly, and let the cheesecake cool inside for about an hour to prevent cracking.
4. Once cool, transfer the cheesecake to the fridge to chill for at least 2 hours, or overnight for best results.

Step 4: Prepare the Blueberry Topping

1. While the cheesecake is chilling, prepare the blueberry topping. In a small saucepan, combine the blueberries, sugar, water, and lemon juice.
2. Cook over medium heat, stirring occasionally, until the blueberries start to break down and release their juices (about 5-7 minutes).
3. Stir in the cornstarch slurry and continue cooking for 1-2 minutes, until the sauce thickens.
4. Remove from heat and allow the topping to cool completely.

Step 5: Assemble the Dessert

1. Once the cheesecake has fully chilled, pour the cooled blueberry topping over the top of the cheesecake.
2. Use a spatula to spread it evenly.
3. Return the cheesecake to the fridge for another 30 minutes to let the topping set.

Step 6: Serve and Enjoy!

1. Carefully remove the cheesecake from the springform pan.
2. Slice and serve the cheesecake with an optional garnish of fresh blueberries or whipped cream.