Step 1: Prepare the Crust

1. Preheat oven to 325°F (160°C) and grease a 9-inch springform pan.
2. In a bowl, mix graham cracker crumbs, sugar, and melted butter until combined.
3. Press the mixture firmly into the bottom of the springform pan.
4. Bake for 8 to 10 minutes, then let it cool completely.

Step 2: Make the Cheesecake Filling

1. In a mixing bowl, beat cream cheese and sugar until smooth.
2. Add eggs one at a time, mixing gently to avoid incorporating too much air.
3. Stir in vanilla extract, sour cream, lemon juice, and lemon zest until well combined.
4. Pour the filling over the cooled crust, smoothing the top with a spatula.

Step 3: Bake the Cheesecake

1. Wrap the springform pan with two layers of aluminum foil and place it in a large baking dish.
2. Pour hot water into the baking dish, filling it halfway up the sides of the pan (water bath method).
3. Bake for 55 to 65 minutes until the edges are set but the center still has a slight jiggle.
4. Turn off the oven, leave the door slightly open, and let the cheesecake cool inside for 30 minutes.
5. Remove from the oven and cool at room temperature before refrigerating for at least 4 hours or overnight.

Step 4: Prepare the Blueberry Topping

1. In a saucepan over medium heat, combine blueberries, sugar, and lemon juice.
2. In a small bowl, mix cornstarch and water to create a slurry, then stir it into the blueberry mixture.
3. Simmer until the sauce thickens, about 5 minutes. Remove from heat and let cool.

Step 5: Assemble and Serve

1. Spread the cooled blueberry topping evenly over the chilled cheesecake.
2. Garnish with extra lemon zest or fresh blueberries if desired.
3. Slice and serve.