Prepare the crust by combining the crushed graham crackers, melted butter, lemon zest, and sugar in a mixing bowl.
Stir until the mixture is evenly moistened.
Transfer the graham cracker mixture to a 9-inch square baking pan.
Using the bottom of a flat cup, press the mixture gently and evenly into the bottom of the pan to form the crust.
Preheat the oven to 350°F.
Bake the crust for 10 to 15 minutes.
Remove the crust from the oven and set it aside to cool slightly.
In a large mixing bowl, combine the softened cream cheese, sugar, fresh lemon juice, eggs, and lemon zest.
Beat until the mixture is smooth and fully combined.
Spoon the cheesecake filling evenly over the cooled crust.
Scatter the fresh blueberries over the cheesecake layer.
Using a butter knife, gently swirl the blueberries into the cheesecake filling.
In a separate bowl, prepare the crumble topping by combining the all-purpose flour, melted butter, and packed brown sugar.
Stir until the mixture resembles coarse crumbs.
Sprinkle the crumble topping evenly over the cheesecake and blueberry layer.
Bake for 35 to 40 minutes, or until the cheesecake layer is set and the topping is lightly baked.
Remove the pan from the oven and allow the bars to cool at room temperature for 1 hour.
Transfer the pan to the refrigerator and chill for at least 1 additional hour.
Once fully chilled, cut into bars.
Serve chilled.