Preheat your oven to 325°F (160°C). Prepare a 9×13-inch baking pan and lightly grease it or line it with parchment paper.

In a mixing bowl, combine the graham cracker crumbs, sugar, and melted butter. Mix until the crumbs are evenly coated and resemble wet sand. Press this mixture firmly into the bottom of the pan.

Bake the crust for 10 minutes. Remove it from the oven and let it cool slightly while you prepare the cheesecake layer.

In a large bowl, beat the softened cream cheese with the sugar until completely smooth.

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

Pour the cheesecake mixture over the cooled crust and spread it evenly using a spatula.

Place the pan in the oven and bake for 25 to 30 minutes, or until the edges are set.

Let it cool to room temperature, then refrigerate for at least 2 to 3 hours until fully chilled and set.

In a saucepan, combine the blueberries, sugar, lemon juice, and water. Cook over medium heat until the berries begin to break down.

If you want a thicker sauce, mix the cornstarch with a little cold water and stir it into the sauce, continuing to cook for another minute until thickened.

Remove from heat and let the sauce cool completely before using it on the cheesecake bars.

Once the cheesecake is fully chilled, cut it into bars using a sharp knife.

Spoon the cooled blueberry sauce over each bar just before serving.