Preheat Oven and Prepare Pan:

Preheat your oven to 325°F (165°C). Line a 9x9-inch baking pan with parchment paper, leaving overhang for easy removal.

Make the Crust:

In a bowl, mix the graham cracker crumbs, melted butter, and sugar until well combined.

Press the mixture evenly into the bottom of the prepared pan. Bake for 8–10 minutes, then set aside to cool.

Prepare the Cheesecake Filling:

In a mixing bowl, beat the softened cream cheese and sugar until smooth and creamy.

Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract and sour cream until fully combined.

Pour the cheesecake filling over the cooled crust, spreading it evenly.

Bake:

Bake the bars for 25–30 minutes, or until the edges are set and the center is slightly jiggly. Let the cheesecake cool to room temperature, then refrigerate for at least 3 hours or overnight.

Prepare the Blueberry Topping:

In a small saucepan, combine the blueberries, sugar, cornstarch, water, and lemon juice. Cook over medium heat, stirring frequently, until the mixture thickens and the blueberries break down slightly (about 5–7 minutes).

Allow the topping to cool completely.

Assemble the Bars:

Spread the cooled blueberry topping evenly over the chilled cheesecake layer.

Slice and Serve:

Lift the bars out of the pan using the parchment overhang. Slice into squares and serve chilled.