1. Preheat oven to 325°F (160°C). Line a springform pan with parchment paper. Combine graham cracker crumbs and melted butter, mix well, and press into the bottom of the pan to form a firm crust. Bake for 10 minutes and let cool.

2. In a large bowl, beat cream cheese until smooth and fluffy. Add sugar, lemon zest, and lemon juice. Mix until well combined. Add eggs one at a time, beating gently and scraping the sides as needed. Stir in sour cream and vanilla extract until just blended.

3. Pour the cheesecake filling over the cooled crust. Tap the pan gently to remove air bubbles. Place the pan in a water bath and bake for 50–60 minutes or until the center is slightly jiggly. Turn off the oven, crack the door, and let it cool inside for 1 hour.

4. Remove from oven and refrigerate for at least 4 hours or overnight for best texture.

5. To make the topping, place blueberries, sugar, lemon juice, and cornstarch in a saucepan over medium heat. Stir and simmer until berries begin to burst and the sauce thickens, about 5–8 minutes. Let cool before using.

6. Spoon the blueberry topping over the chilled cheesecake. Garnish with whipped cream and lemon slices if desired. Slice with a hot, clean knife and serve chilled.