Preheat oven to 325°F (165°C). Grease the sides of a 9‑inch springform pan and line the bottom with parchment paper if desired.

In a medium bowl, mix the graham cracker crumbs, 2 tablespoons granulated sugar, and a pinch of salt. Stir in 6 tablespoons melted unsalted butter until the mixture resembles wet sand. Press firmly into the bottom of the pan and about 1/2 inch up the sides. Bake for 10 minutes, then set aside to cool.

In a small bowl, gently toss the blueberries with 2 tablespoons granulated sugar, 1 tablespoon cornstarch (or flour), and 1 tablespoon lemon juice. Set aside.

In another bowl, mix the light brown sugar, 1/2 cup all‑purpose flour, and oats. Drizzle in 4 tablespoons melted unsalted butter and stir until small clumps form. Set aside.

In a large mixing bowl, beat the cream cheese until smooth and fluffy. Gradually add 1 cup granulated sugar, mixing on low. Add 1 teaspoon vanilla extract, then the 2 tablespoons all‑purpose flour, mixing just until combined.

Beat in the sour cream until the mixture is silky. Add the eggs one at a time, mixing on low and only until each is incorporated. Do not over‑mix.

Pour the batter over the cooled crust and smooth the top with a spatula. Scatter the blueberry mixture evenly over the batter, then sprinkle the crumble topping in a thin, even layer.

Place the pan on a baking sheet and bake for 60–70 minutes, until the edges are set and the center is only slightly jiggly. Turn off the oven, crack the door with a wooden spoon, and let the cheesecake cool inside for 1 hour. Refrigerate for at least 6 hours, preferably overnight, before slicing.