Preheat oven to 325°F (165°C) and line a 9×9-inch pan with parchment paper

Mix graham cracker crumbs, sugar, and melted butter until evenly combined

Press firmly into the pan and bake for 10 minutes

Cook blueberries, sugar, and lemon juice over medium heat until berries burst

Stir in cornstarch slurry and simmer until thickened, then cool

Beat cream cheese until smooth, then mix in sugar

Add eggs one at a time, mixing just until combined

Mix in sour cream, lemon juice, lemon zest, and vanilla

Pour filling over cooled crust

Spoon blueberry sauce over the top and gently swirl

Bake for 38–42 minutes until edges are set and center slightly jiggles

Turn off oven, crack door, and cool inside for 30 minutes

Cool completely, then refrigerate for at least 4–6 hours

Lift out and slice with a sharp knife