Preheat your oven to 325°F (163°C) and line a 9x13-inch baking pan with parchment paper.

Combine graham cracker crumbs, granulated sugar, and melted unsalted butter in a bowl. Press into the bottom of the pan and bake for 10 minutes.

In a large bowl, beat the cream cheese and sugar until smooth. Add eggs one at a time, mixing after each, then fold in flour and blueberries.

Pour cheesecake filling over the cooled crust and smooth the top. Bake for 35-40 minutes until edges are set and center is slightly jiggly.

Let the bars cool in the pan at room temperature before refrigerating for at least 2 hours.

For the optional jam topping, boil blueberries, sugar, water, and lemon juice until thickened, about 10 minutes. Cool and drizzle over the bars before serving.