Prepare the Crust

Preheat the oven to 325°F (160°C). Line an 8x8-inch baking pan with parchment paper, leaving some overhang for easy removal.

In a mixing bowl, combine graham cracker crumbs, sugar, and melted butter. Mix until evenly moistened.

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

Make the Blueberry Swirl

In a small saucepan over medium heat, combine blueberries, sugar, and lemon juice. Cook until the blueberries burst and the mixture thickens slightly (about 5 minutes). Set aside to cool, then puree or mash lightly.

Prepare the Cheesecake Filling

In a large mixing bowl, beat the cream cheese and sugar with an electric mixer until smooth and creamy.

Add the eggs one at a time, mixing well after each addition.

Mix in the sour cream, lemon juice, lemon zest, and vanilla extract until combined.

Assemble and Bake

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

Drop small spoonfuls of the blueberry mixture onto the filling. Use a toothpick or skewer to gently swirl the blueberry mixture into the cheesecake layer.

Bake for 35-40 minutes, or until the center is just set. Remove from the oven and let cool to room temperature, then refrigerate for at least 4 hours (preferably overnight).

Serve

Use the parchment paper to lift the bars out of the pan. Slice into squares or rectangles and serve chilled.