Preheat the oven to 325°F (160°C).

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

In another bowl, beat the softened cream cheese until smooth. Add sour cream, granulated sugar, eggs, and vanilla extract. Mix until combined.

Gently fold in the fresh blueberries, cornstarch, and lemon juice into the cream cheese mixture.

Pour the cream cheese mixture over the prepared crust in the springform pan.

In a separate bowl, combine oats, brown sugar, all-purpose flour, and cinnamon (if using). Sprinkle the oat mixture over the cheesecake filling.

Bake in the preheated oven for about 60 minutes or until the edges are set and the center is slightly jiggly.

Allow to cool at room temperature, then refrigerate for at least 4 hours before serving.