Preheat the oven to 325°F.

In a mixing bowl, combine the graham cracker crumbs, melted unsalted butter, and granulated sugar. Press into the bottom of a springform pan to form the crust.

In another bowl, beat together the cream cheese and sour cream until smooth. Add the granulated sugar and vanilla extract, and mix well.

Add eggs one at a time, mixing just until combined after each addition.

Gently fold in the fresh blueberries, lemon juice, and cornstarch.

Pour the cheesecake filling over the prepared crust in the springform pan.

In a separate bowl, mix together the oats, brown sugar, all-purpose flour, cinnamon, and additional unsalted butter until crumbly.

Sprinkle the oat crumble over the cheesecake filling.

Bake for 50 minutes or until the center is set (not jiggly).

Allow to cool before serving.